صحيح ابن خزيمه
Sahih Ibn Khuzaymah
جماع أبواب الكلام المباح فى الصلاة والدعاء والذكر، ومسألة الرب عز وجل وما يضاهي هذا ويقاربهChapters on Permissible Speech, Supplication, and Remembrance in Prayer
(305) بَابُ ذِكْرِ الْكَلَامِ فِي الصَّلَاةِ جَهْلًا مِنَ الْمُتَكَلِّمِ305 Chapter: Speaking in Prayer Out of Ignorance.
Hadith Q859
وَالدَّلِيلِ عَلَى أَنَّ الْكَلَامَ لَا يَقْطَعُ الصَّلَاةَ إِذَا لَمْ يَعْلَمِ الْمُتَكَلِّمُ أَنَّ الْكَلَامَ فِي الصَّلَاةِ مَحْظُورٌ غَيْرُ مُبَاحٍ
And the explanation of the evidence that if the person speaking does not know that speaking during prayer is prohibited, then his prayer is not invalidated by his speech.
