صحیح ابن حبان
Ibn Hibban
كتاب الصلاة
Book of Prayer
باب النوافل - ذكر البيان بأن الداخل المسجد والإمام يخطب إنما أمر أن يركع ركعتين خفيفتين قبل الجلوس
Section on voluntary prayers – clarification that one entering the mosque while the imam is preaching is instructed to pray two light rak’ahs before sitting
1 hadith
Hadith 2501
Sayyiduna Jabir (may Allah be pleased with him) narrates: A man entered the mosque while the Prophet Muhammad (peace and blessings be upon him) was delivering the sermon on Friday. The Prophet Muhammad (peace and blessings be upon him) said to him: Before sitting down, perform two short rak‘ahs.