Jami` at-Tirmidhi, Volume 3, Book 19, Hadith 1593 (DarusSalam) ⓘ
Narrated Ibn 'Umar: "We used to pledge to the Messenger of Allah to hear and obey." So he would say to us: "As much as you are able." [Abu 'Eisa said:] This Hadith is Hasan Sahih.
حَدَّثَنَا عَلِيُّ بْنُ حُجْرٍ، أَخْبَرَنَا إِسْمَاعِيلُ بْنُ جَعْفَرٍ، عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ، عَنِ ابْنِ عُمَرَ، قَالَ كُنَّا نُبَايِعُ رَسُولَ اللَّهِ صلى الله عليه وسلم عَلَى السَّمْعِ وَالطَّاعَةِ فَيَقُولُ لَنَا " فِيمَا اسْتَطَعْتُمْ " . قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ كِلاَهُمَا .
also referenced under: Hadith 1593 (Reference) & Book 21, Hadith 55 (In-Book)