مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3358
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated from Ibn ‘Abbas (رضي الله عنه) that The Messenger of Allah (ﷺ) came out of the outhouse and some food was brought to him. They said: Shouldn't we bring you water for wudoo’? He said: "when I want to pray I will do wudoo'."
Musnad Ahmad 3382Its isnad is saheeh, Muslim (374)]