Sahih al-Bukhari 4806
Sahih al-Bukhari · Book 65: Prophetic Commentary on the Qur'an (Tafseer of the Prophet (pbuh)) · The Statement of Allah the Exalted: "And, verily, Yūnus (Jonah) was one of the Messengers." (V.37:139)
Narrated Al-Awwam:
حَدَّثَنَا مُحَمَّدُ بْنُ بَشَّارٍ ، حَدَّثَنَا غُنْدَرٌ ، حَدَّثَنَا شُعْبَةُ ، عَنِ الْعَوَّامِ ، قَالَ سَأَلْتُ مُجَاهِدًا عَنِ السَّجْدَةِ، فِي ص قَالَ سُئِلَ ابْنُ عَبَّاسٍ فَقَالَ {أُولَئِكَ الَّذِينَ هَدَى اللَّهُ فَبِهُدَاهُمُ اقْتَدِهْ} . وَكَانَ ابْنُ عَبَّاسٍ يَسْجُدُ فِيهَا .
I asked Muhajid regarding the prostration in Surat Sa`d. He said, "Ibn `Abbas was asked the same question and he said, 'Those are they (the prophets) whom Allah had Guided. So follow their guidance." (6.90) Ibn `Abbas used to perform a prostration (on reading this Sura).