Oaths and Vows (Kitab Al-Aiman Wa Al-Nudhur) 
Dawud :: Book 21 : Hadith 3255
Narrated Abdullah ibn Umar:
The Prophet (peace_be_upon_him) said: If anyone says when swearing an oath: "If Allah wills," he makes an exception.
Oaths and Vows (Kitab Al-Aiman Wa Al-Nudhur)
Dawud :: Book 21 : Hadith 3255
Narrated Abdullah ibn Umar:
The Prophet (peace_be_upon_him) said: If anyone says when swearing an oath: "If Allah wills," he makes an exception.