When the Imam is delivering the Khutba, a light two Rak‘a Salat (prayer) (Tahayyat-ul Masjid)

Narrated Jabir:

A man entered the Mosque while the Prophet 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 Rakat."

حَدَّثَنَا عَلِيُّ بْنُ عَبْدِ اللَّهِ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنْ عَمْرٍو، سَمِعَ جَابِرًا، قَالَ دَخَلَ رَجُلٌ يَوْمَ الْجُمُعَةِ وَالنَّبِيُّ ﷺ يَخْطُبُ فَقَالَ " أَصَلَّيْتَ ". قَالَ لاَ. قَالَ " فَصَلِّ رَكْعَتَيْنِ ".