The government's motion calling for a "strong humanitarian response" with possible military action in Syria, following an alleged chemical attack near Damascus last week, has been defeated 285-272 in the House of Commons.
Thirty Conservative and nine Liberal Democrat MPs voted against the government's motion.
Here are the reactions of Ed Miliband and David Cameron to the vote, followed by some of the key contributions from the House of Commons and the House of Lords earlier.
Party leaders react
Ed Miliband said: "Can the prime minister confirm to the House that he will not use the Royal Prerogative to order the UK to be part of military action, given the will of the House that has been expressed tonight, before there has been another vote in this House of Commons?"
David Cameron replied: "I can give that assurance. Let me say the House has not voted for either motion tonight. I strongly believe in the need for a tough response to the use of chemical weapons but I also believe in respecting the will of this House of Commons."
He added: "It is clear to me that the British Parliament, reflecting the views of the British people, does not want to see British military action. I get that and the government will act accordingly."
Before the vote: Prime Minister David Cameron
"Interfering in another country's affairs should not be undertaken except in the most exceptional circumstances. It must be a humanitarian catastrophe and it must be a last resort.
"But by any standards, this is a humanitarian catastrophe, and if there are no consequences for it, there is nothing to stop [President Bashar al-] Assad and other dictators from using these weapons again and again.
"Doing nothing is a choice. It's a choice with consequences. And these consequences in my view would not just be about President Assad and his future use of chemical weapons."
Labour leader Ed Miliband
"There will be some in this House who say Britain should not contemplate action, even when it is limited, because we do not know precisely the consequences that will follow.
"I'm not with those who rule out action - the horrific events unfolding in Syria do ask us to consider the options available.
"But we owe it to the Syrian people, to our own country and to the future security of our world to scrutinise any plans on the basis of the consequences they have."
Deputy Prime Minister Nick Clegg
"The sole aim is to, is to relieve humanitarian suffering by deterring and disrupting the further use of chemical weapons.
"Nothing more, nothing less. Not invasion. Not regime change. Not about entering Syrian, into the Syrian conflict.
"Not about arming the rebels. If I may, if I may just make little bit of progress. Not boots on the ground. President Obama's intentions are highly limited and so are ours."
Angus Robertson, SNP leader at Westminster
"We cannot ignore the lessons of the calamitous Iraq war. We need safeguards to ensure that all is done to provide evidence about chemical weapons and support the United Nations and international law.
"We need a coherent and comprehensive strategy which fully takes in the consequences of intervention. What is currently a calamity for the people of Syria could worsen and become a conflagration across the Middle East."
Former Conservative Foreign Secretary Sir Malcolm Rifkind
"If they get away with what they have done, if there is no significant international response of any kind, then we can be absolutely certain that the forces within Damascus will be successful in saying we must continue to use these whenever there is a military rationale for doing so.
"There is no guarantee that a military strike against military targets will work, but there is every certainty that if we don't make that effort to punish and deter, then these actions will indeed continue."
Former Labour Foreign Secretary Jack Straw
"[The prime minister] sought to draw a distinction in his speech between 'our response to war crimes and taking sides in the conflict', I say however much he struggles to make that distinction, if we take an active part in military action, which I do not rule out... then let us be clear that we shall be taking sides, there's no escape from that and we shall be joining with the rebels, with all the consequences that arise from that, and not maintaining a position of neutrality."
Former Lib Dem leader Lord Ashdown
"It seems to me that this matter turns on a single question: Do you take more risk, danger through acting or do you run a greater risk through lack of action?...
"The aim is to act as a bulwark to international law and above all to protect one of the few pillars of international law that has been in existence for 100 years or more - that against the use of chemical weapons and against gas."
Archbishop of Canterbury Justin Welby
"If we take action that diminishes the chances of peace and reconciliation, when inevitably a political solution has to be found whether in the near term or long term future, then we will have contributed to more killing and this war will be deeply unjust.
"In consequence, I feel that any interventions must be effective in terms of preventing any further use of chemical weapons. I have not yet heard that has been adequately demonstrated as likely."
Respect MP George Galloway
"There is no compelling evidence, to use the leader of the opposition's words, that the Assad regime is responsible for this crime, yet.
"Not that they are not bad enough to do it - everybody knows they are bad enough to do it - the question is are they mad enough to do it?
"To launch a chemical weapons attack in Damascus on the very day that a United Nations chemical weapons inspection team arrives in Damascus must be a new definition of madness."
Green MP Caroline Lucas
"I remain concerned about the impact of flouting international law.
"To intervene without the due resolution sends a message to everyone else that international law can be ignored when it's inconvenient and as the law of the jungle takes hold it will be increasingly difficult to condemn similar actions by others. "
Richard Ottaway, chairman of foreign affairs committee
"In effect, it [the opinion that action is legal without a UN resolution]means the United Nations is now redundant and the humanitarian doctrine has legs of its own.
"It can be interpreted virtually any way the parties wish and I hope when the dust has settled from this affair, this House and the United Nations revisit the responsibility to protect because I believe at present it is not working the way it was intended."
Conservative MP John Redwood
"We have to ask, through the government, how many soldiers and managers of soldiers and officers would you need to kill in order to guarantee that Assad will not do it again?
"I fear when you have someone as mad and bad as Assad, the answer might be very high. The question is would we want to do that much, are we sure it will work?"
Former Tory leadership contender David Davis
"We do not want to be conned into a war in effect by actions designed just to do that.
"There are plenty of facts around, or at least reported facts, reported that the UN representative for human rights in Syria thought there was concrete evidence of rebels having sarin gas.
"Reports that the Turkish authorities arrested 12 al-Nusra fighters with two kgs of sarin gas.
"Other reports that Hezbollah fighters are in Beirut hospitals suffering from the effects of sarin gas.
"Now I think a number of people have said we must have clear evidence to show this House that if there is a casus belli (justification for war), it's real, not confected, not constructed, and that means perhaps a more aggressive disclosure of intelligence than we would normally have."
Labour MP Kate Hoey
"We should be calling in the Russian ambassador and actually saying we are going to expel you from this country if you don't do something and change the attitude of Russia.
"Military action is a very, very last option and I do not believe it is something we should go down the line."
Lorely Burt, chairman of the Lib Dem parliamentary party
"I do support action but not a military solution.
"I want to make it clear that, unless we act with a wide international coalition with full and transparent internationally agreed law, I would not support a vote to take military action in the future."