Mukhtasar Bukhari (Abridged) 518 — If someone arrives during

Narrated Jabir bin Abdullah (may Allah be pleased with him): A man came (to the mosque) while the Prophet (peace and blessings of Allah be upon him) was delivering the sermon, and sat down. The Prophet (peace and blessings of Allah be upon him) asked him: "Have you prayed two rak'ahs (Tahiyyat al-Masjid)?" He replied: "No." The Prophet (peace and blessings of Allah be upon him) said: "Get up and pray two rak'ahs."