وَعَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ
قَالَ: كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: إِذَا اجْتَهَدَ فِي الْيَمِينِ قَالَ: «لَا وَالَّذِي نفس أَبُو الْقَاسِم بِيَدِهِ»
Abu Said al-Khudri told that when God’s Messenger swore strongly he said, “No, by Him in whose hand is the soul of Abu Qasim.”
Mishkat al-Masabih 3289, Book 16, Oaths and Vows, Hadith 17. 1 min read