The word(s) "letting" appears 3 time(s) in 3 verse(s) in Quran in Mohsin Khan translation.

(1) And (remember) when We rescued you from Fir'aun's (Pharaoh) people, who were afflicting you with the worst torment, killing your sons and letting your women live. And in that was a great trial from your Lord.

(2) And (remember) when Musa (Moses) said to his people: "Call to mind Allah's Favour to you, when He delivered you from Fir'aun's (Pharaoh) people who were afflicting you with horrible torment, and were slaughtering your sons and letting your women alive; and in it was a tremendous trial from your Lord."

(3) Verily, Fir'aun (Pharaoh) exalted himself in the land and made its people sects, weakening (oppressing) a group (i.e. Children of Israel) among them: killing their sons, and letting their females live. Verily, he was of the Mufsidun (i.e. those who commit great sins and crimes, oppressors, tyrants).