Sahih Muslim 488
Ma'dan b. Talha reported:
I met Thauban, the freed slave. of Allah's Messenger (ﷺ), and asked him to tell me about an act for which, if I do it, Allah will admit me to Paradise, or I asked about the act which was loved most by Allah. He gave no reply. I again asked and he gave no reply. I asked him for the third time, and he said: I asked Allah's Messenger (ﷺ) about that and he said: Make frequent prostrations before Allah, for you will not make one prostration without raising you a degree because of it, and removing a sin from you, because of it. Ma'dan said that then lie met Abu al-Darda' and when he asked him, he received a reply similar to that given by Thauban.
حَدَّثَنِي زُهَيْرُ بْنُ حَرْبٍ، حَدَّثَنَا الْوَلِيدُ بْنُ مُسْلِمٍ، قَالَ سَمِعْتُ الأَوْزَاعِيَّ، قَالَ حَدَّثَنِي الْوَلِيدُ بْنُ هِشَامٍ الْمُعَيْطِيُّ، حَدَّثَنِي مَعْدَانُ بْنُ أَبِي طَلْحَةَ الْيَعْمَرِيُّ، قَالَ لَقِيتُ ثَوْبَانَ مَوْلَى رَسُولِ اللَّهِ صلى الله عليه وسلم فَقُلْتُ أَخْبِرْنِي بِعَمَلٍ أَعْمَلُهُ يُدْخِلُنِي اللَّهُ بِهِ الْجَنَّةَ ‏.‏ أَوْ قَالَ قُلْتُ بِأَحَبِّ الأَعْمَالِ إِلَى اللَّهِ ‏.‏ فَسَكَتَ ثُمَّ سَأَلْتُهُ فَسَكَتَ ثُمَّ سَأَلْتُهُ الثَّالِثَةَ فَقَالَ سَأَلْتُ عَنْ ذَلِكَ رَسُولَ اللَّهِ صلى الله عليه وسلم فَقَالَ ‏
"‏ عَلَيْكَ بِكَثْرَةِ السُّجُودِ لِلَّهِ فَإِنَّكَ لاَ تَسْجُدُ لِلَّهِ سَجْدَةً إِلاَّ رَفَعَكَ اللَّهُ بِهَا دَرَجَةً وَحَطَّ عَنْكَ بِهَا خَطِيئَةً ‏"‏ ‏.‏ قَالَ مَعْدَانُ ثُمَّ لَقِيتُ أَبَا الدَّرْدَاءِ فَسَأَلْتُهُ فَقَالَ لِي مِثْلَ مَا قَالَ لِي ثَوْبَانُ ‏.‏