Qad saddaqta arru'ya inna kathalika najzee almuhsineen (surah Assaaffat: 105)

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(37:105) you have indeed fulfilled your dream. *63 Thus do We reward the good-doers.' *64

Qad saddaqtar ru`yaa; innaa kazaalika najzil muhsineen

*63) That is, "We did not make you see in the dream that you had actually slaughtered your son and he had died, but that you were slaughtering him. That Vision you have fulfilled. Now, it is not Our will w take the life of your child: the actual object of the vision has been fulfilled by your submission and preparation to sacrifice him for Our sake."
*64) That is, "We do not subject the people who adopt the righteous way to trials in order to involve them in trouble and distress and affliction just for the sake of it, but these trials are meant to bring out their excellencies and to exalt them to high ranks, and then We deliver them also safe and sound from the dilemma in which We place them for the sake of the trial. Thus, your willingness and preparation to sacrifice yow son is enough to entitle you to be exalted to the rank that could be attained only by the one who would actually have slaughtered his son for Our approval and pleasure. Thus, We have saved the life of yow child as well as exalted you to this high rank. "