Sahih al-Bukhari 4852
Sahih al-Bukhari · Book 65: Prophetic Commentary on the Qur'an (Tafseer of the Prophet (pbuh)) · The Statement of Allah the Exalted: "...And glorify the praises of your Lord, before the rising of the sun and before (its) setting (i.e., the Fajr, Ẓuhr and 'Aṣr prayers) ." (V.50:39)
Narrated Mujahid:
حَدَّثَنَا آدَمُ ، حَدَّثَنَا وَرْقَاءُ ، عَنِ ابْنِ أَبِي نَجِيحٍ ، عَنْ مُجَاهِدٍ ، قَالَ ابْنُ عَبَّاسٍ أَمَرَهُ أَنْ يُسَبِّحَ، فِي أَدْبَارِ الصَّلَوَاتِ كُلِّهَا . يَعْنِي قَوْلَهُ {وَأَدْبَارَ السُّجُودِ}
Ibn `Abbas said, "Allah ordered His Prophet to celebrate Allah's praises after all prayers." He refers to His Statement: 'After the prayers.' (50.40)