Abdullah bin Marrah al-Kharfi عبد الله بن مرة الهمداني الخارفي · The Book of Oaths and Vows

"There is no vow and no oath concerning that which one does not possess, nor to commit sin, nor to sever the ties of kinship."

"Whoever swears an oath and says: 'If Allah wills', then if he wishes he may go ahead, and if he wishes he may not, without having broken his oath."

"Actions are but by intentions, and each person will have but that which he intended. Thus, he whose emigration was for the sake of Allah and His Messenger, his emigration was for the sake of Allah and His Messenger, and he whose emigration was to achieve some worldly gain or to take some woman in marriage, his emigration was for that for which he emigrated."