مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2411
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
Isma'eel bin Rabee'ah bin Hisham bin Ishaq bin ‘Abdullah bin Kinanah said: I heard my grandfather Hisham bin Ishaq bin 'Abdullah narrate that his father said: Al-Waleed sent word asking Ibn 'Abbas (رضي الله عنه): What did the Messenger of Allah (ﷺ) do when he prayed for rain (istisqa')? He said: The Messenger of Allah (ﷺ) went out wearing scruffy clothes and with a humble attitude, to the prayer place, then he prayed two rak'ahs as he prayed on (Eid) al-Fitr and (Eid) al-Adha.
Musnad Ahmad 2423Hasan]