صحیح ابن حبان
Ibn Hibban
كتاب الصلاة
Book of Prayer
باب سجود السهو - ذكر البيان بأن الساجد سجدتي السهو بعد السلام عليه أن يتشهد ثم يسلم ثانيا
Chapter on Prostration of Forgetfulness - Clarification that one who prostrates after salam should recite tashahhud and then salam again
2 hadith
Hadith 2670
Sayyiduna Imran bin Husayn (may Allah be pleased with him) narrates: The Prophet (peace and blessings of Allah be upon him) led those people in prayer. He performed the prostration of forgetfulness (sajda sahw) twice, then he recited the tashahhud and concluded the prayer with salam. In narrating this report, the narrator named Ansari is unique; Ibn Sirin has not narrated any other report from Khalid except this hadith, although Khalid is his student.
Hadith 2671
Sayyiduna Imran bin Husain (may Allah be pleased with him) narrates: The Prophet Muhammad (peace and blessings be upon him) concluded the ‘Asr prayer after three rak‘ahs. Sayyiduna Khirbaq (may Allah be pleased with him) submitted to him: O Messenger of Allah (peace be upon him)! Did you forget, or has the prayer been shortened? The Prophet (peace be upon him) asked: Is Khirbaq speaking the truth? They replied: Yes! You stood up, performed one rak‘ah, performed the prostration of forgetfulness twice, and then concluded the prayer with salam.