All praise is for Allaah, alone, and prayers and peace be upon the last and final Prophet. Anas (RA) said that he heard the Prophet (SAW) say: "That I sit with people remembering Almighty Allah from the morning (Fajr) prayer until sunrise is more beloved to me than freeing four slaves from among the Children of Isma'il. That I sit with people remembering Allah from the afternoon ('Asr) prayer until the sun sets is more beloved to me than freeing four slaves from among the Children of Isma'il."
This was reported by Abu Dawud (no. 3667). Al-Albani graded it good in Sahih Abu Dawud 2/698.