Sahih al-Bukhari 5982
Sahih al-Bukhari · Book 78: Good Manners and Form (Al-Adab) · Superiority of good relations with relatives
Narrated Abu Ayyub Al-Ansari:
حَدَّثَنَا أَبُو الْوَلِيدِ ، حَدَّثَنَا شُعْبَةُ ، قَالَ أَخْبَرَنِي ابْنُ عُثْمَانَ ، قَالَ سَمِعْتُ مُوسَى بْنَ طَلْحَةَ ، عَنْ أَبِي أَيُّوبَ، قَالَ قِيلَ يَا رَسُولَ اللَّهِ، أَخْبِرْنِي بِعَمَلٍ، يُدْخِلُنِي الْجَنَّةَ.
It was said" "O Allah's Messenger! Inform me of a deed which will make me enter Paradise." (continues through a different chain in the next hadith)