“He specifies His grace (from whom He wills) to whom He wills! Allah is the Azim, the possessor of bounty.”
Sayyed Abbas Sadr-Ameli
He specializes for His mercy whom He pleases, and Allah is the Lord of Mighty Grace
Al-muntakhab fi tafsir al-Qur'an al-Karim
"He extends His mercy to whom He will and He is the source of sufficient grace which abounds in whom He will and of the efficacious grace which effects the end for which it is given"