(33) باب مَنْ جَاءَ وَالإِمَامُ يَخْطُبُ صَلَّى رَكْعَتَيْنِ خَفِيفَتَيْنِ
Narrated Jabir:
A man entered the Mosque while the Prophet (ﷺ) was delivering the Khutba. The Prophet (ﷺ) said to him, "Have you prayed?" The man replied in the negative. The Prophet (ﷺ) said, "Pray two rak`at."
Reference: Sahih al-Bukhari 931
In-book reference: Book 11, Hadith 55
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 2, Book 13, Hadith 53