مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2100
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated from Ibn 'Abbas (رضي الله عنه) that One of the wives of the Prophet (ﷺ) did ghusl from janabah, and the Prophet (ﷺ) did wudoo' with her left-over water. She said something about that to him and he said: “Nothing makes water najis (impure).”
Musnad Ahmad 2102Saheeh because of corroborating evidence]