from 'Abdullah bin Unais Al-Juhni who said: "The Messenger of Allah (ﷺ) said: 'Indeed among the worst of the major sins is Shirk with Allah, disobeying the parents, the false oath, and none insists on taking an oath in which he swears, including the like of a wing of a mosquito (of falsehood) in it - except that a spot is placed in his heart until the Day of Judgement.'"