مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2573
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated from Ibn 'Abbas (رضي الله عنه) from the Prophet (ﷺ): "I have been commanded to prostrate on seven, and not to tuck up my hair or garment."
Musnad Ahmad 2588lts isnad saheeh, al-Bukhari (809) and Muslim (490)]