Sunnah.com reference : Book 2, Hadith 253English translation : Book 2, Hadith 346Arabic reference : Book 2, Hadith 351
Narrated Rabi'ah bin Ka'b al-Aslami (RA):
The Prophet (ﷺ) said to me, "Ask." I said, "I ask your company in Paradise." He replied, "Or something else?" I said, "That is it (i.e. that is what I desire)." He said, "Then help me to achieve this for you by devoting yourself often to prostration."

[Reported by Muslim].
عَنْ رَبِيعَةَ بْنِ كَعْبٍ الْأَسْلَمِيِّ ‏-رِضَى اَللَّهُ عَنْهُ‏- قَالَ : { قَالَ لِي اَلنَّبِيُّ ‏- صلى الله عليه وسلم ‏-سَلْ .‏ فَقُلْتُ : أَسْأَلُكَ مُرَافَقَتَكَ فِي اَلْجَنَّةِ .‏ فَقَالَ : أَوَغَيْرَ ذَلِكَ ? , قُلْتُ : هُوَ ذَاكَ , قَالَ : " فَأَعِنِّي عَلَى نَفْسِكَ بِكَثْرَةِ اَلسُّجُودِ }  رَوَاهُ مُسْلِمٌ .‏  1‏‏1 ‏- صحيح .‏ رواه مسلم ( 489 )‏ .‏