The Hadith of Slaughter
Ya’qūb said, my father told us from Ibn Is’hāq, who said Yahyā ibn ‘Urqah ibn az-Zubayr told me from his father from ‘Abdullāh ibn ‘Amr al-‘Ās, who said:
I said to him, “What is the worst act of enmity that the Quraysh had done against the Messenger of Allāh?”
He replied, “I went to Al-Hijr one day, and their dignitaries were there talking about the Messenger of Allāh…
So they said, “We never tolerated a man like the way we did Muhammad… He has mocked our elders, cursed our forefathers, criticized our religion, divided our community, and attacked our gods! We indeed have been very patient with him regarding a grave matter.”
While they were at that state, the Messenger of Allāh (salutations and blessings be upon him) came walking to Ar-Rukn.
Then he went around the Ka’bah (making Tawāf three times). When he passed by them, they started to mock him by repeating some of his (own) sayings. I looked at the Prophet and could see the anger in his face. And when he passed by them the second time, they mocked him again, and I saw the anger in his face (once more)- then he walked (away). Then when he passed by them for the third time and they had mocked him again – the Prophet (salutations and blessings be upon him) replied:
تسمعون يا معشر قريش أما والذي نفس محمد بيده لقد جئتكم بالذبح
“O people of Quraysh! Hear this: By Him in Whose Hand is the soul of Muhammad- I have come to you, to slaughter you.”
His words struck them so severely, that there wasn’t any man from amongst them, except it was as if there was a bird falling upon his head (i.e. they were shocked, terrorized, and dumbfounded) – such that even the one who was the most wickedly harsh against the Prophet before this, was saying the most kind and tender words he could think of; such that even one of them said, “O Abul-Qāsim (Muhammad): Go! Go, O righteous one! Indeed, By Allāh, you are not ignorant!” So the Messenger of Allāh left.
The next day, they gathered together to meet at Al-Hijr and I was with them. They asked each other, “Do you remember what he said to you, and what you said to him? To such a degree, that he manifested to you that which you hate, yet you let him go!” So when they were in this state, the Messenger showed up again. So they all immediately surrounded him, and interrogated, “Are you the one who is mocking our gods and our religion?” The Prophet replied, “Yes. I am the one who says these things.”
I saw one of them (beginning to) pull the garment of the Prophet, but Abū Bakr jumped and stood between them and him. While crying, Abū Bakr said,
*أتقتلون رجلا أن يقول ربي الله
“?Would you kill a man because he says: My Lord is Allāh” [Quran Ghāfir: 28]
Upon that, they left him. This was the worst thing I saw from the Quraysh against the Prophet (salutations and blessings be upon him).
- - - End of Hadīth.
Narrated by Imām Ahmad ibn Hanbal رحمه الله in his Musnad (11/203, # 7036). Imām Ahmad Shākir رحمه الله*******declared its chain to be authentic, and said, “Isnāduhu Sahīh.”
He also mentioned that it is narrated by Ibn Hajar al-Haythamī in Majma’ Az-Zawā’id (6/15-16), and was pointed to by Ibn Hajar al-‘Asqalānī in Al-Fat’h (7/128), and Ibn Kathīr mentioned that it was narrated by al-Bayhaqī in At-Tārīkh (3/46).
Source; http://forums.islamicawakening.com/f44/hadith-slaughter-488/
It seems the hadith of slaughter came into effect when many of the great leaders of the Quraysh (who abused the Prophet) were killed in the Battle of Badr. Allah knows best.