al-Mu’jam al-Kabir, Imam Tabarani, Publish: Maqtaba Ibn Taimmiyah, Qahira
Narrated Maymuna the Mother of the believers said: “The Messenger of Allah Muhammad (upon him blessings and peace), was sleeping with me one night and he got up to make ablution and pray. I heard him say during his ablution in the dead of night: [(Labbayka labbayka labbayka) – [like this,] three times – then: (nus.irta nus.irta nus.irta) [like this,] three times. When he came out, I asked him, “Messenger of Allah, I heard you say, during your ablution, ‘In your service!’ three times, and ‘To your defense!’ three times, as if you were addressing someone. Was there someone with you?” He replied: “This was the poetry champion (rajiz) of the Banu Ka`b” – one of the sub-tribes of the Khuza`a – “invoking my aid (yastas.rikhunî) and asserting that the Quraysh had helped the Banu Bakr against them.
The latter had allied themselves with the Quraysh the day of the Hudaybiya truce while the Khuza`a had allied themselves with the Prophet Muhammad (upon him blessings and peace), and he became duty-bound to defend them. The support of the Quraysh for the Banu Bakr against the Khuza`a was therefore a violation of their truce with the Messenger of Allah, upon him blessings and peace. This incident was the catalyst for the conquest of Makka and, immediately afterwards, he prepared himself to enter it and conquered it. [al-Mu’jam al-Kabir, Imam Tabarani Volume 023, Page 433-4, Hadith Number 1052]