(34) باب مَا جَاءَ فِي بَيْعَةِ النَّبِيِّ صلى الله عليه وسلم
Narrated Ibn 'Umar:
"We used to pledge to the Messenger of Allah (ﷺ) to hear and obey." So he would say to us: "As much as you are able."[Abu 'Eisa said:] This Hadith is Hasan Sahih.
Reference: Jami` at-Tirmidhi 1593
In-book reference: Book 21, Hadith 55
English translation: Vol. 3, Book 19, Hadith 1593