Sahih Muslim 489
Rabi'a b. Ka'b said: I was with Messenger of Allah ﷺ one night. and I brought him water and what he required. He said to me: Ask (anything you like). I said: I ask your company in Paradise. He (the Holy Prophet) said: Or anything else besides it. I said: That is all (what I require). He said: Then help me to achieve this for you by deyoting yourself often to prostration.
حَدَّثَنَا الْحَكَمُ بْنُ مُوسَى أَبُو صَالِحٍ، حَدَّثَنَا هِقْلُ بْنُ زِيَادٍ، قَالَ سَمِعْتُ الأَوْزَاعِيَّ، قَالَ حَدَّثَنِي يَحْيَى بْنُ أَبِي كَثِيرٍ، حَدَّثَنِي أَبُو سَلَمَةَ، حَدَّثَنِي رَبِيعَةُ بْنُ كَعْبٍ الأَسْلَمِيُّ، قَالَ كُنْتُ أَبِيتُ مَعَ رَسُولِ اللَّهِ ﷺ فَأَتَيْتُهُ بِوَضُوئِهِ وَحَاجَتِهِ فَقَالَ لِي " سَلْ " . فَقُلْتُ أَسْأَلُكَ مُرَافَقَتَكَ فِي الْجَنَّةِ . قَالَ " أَوَغَيْرَ ذَلِكَ " . قُلْتُ هُوَ ذَاكَ . قَالَ " فَأَعِنِّي عَلَى نَفْسِكَ بِكَثْرَةِ السُّجُودِ " .