It is narrated from Hazrat Abu Saeed Khudri (may Allah be pleased with him) that when the Prophet (peace and blessings be upon him) would take a firm oath on something, he would say: "No, by Him in Whose Hand is the soul of Abu al-Qasim."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 11444
Hadith Gradingحکم دارالسلام:إسناده ضعيف لجهالة عاصم بن شميخ، وسيأتي بإسناد صحيح برقم: 11537