The word(s) "stern" appears 4 time(s) in 4 verse(s) in Quran in Abdullah Yusuf Ali translation.

(1) Thou wast not on the Western side when We decreed the Commission to Moses, nor wast thou a witness (of those events).

(2) O ye who believe! save yourselves and your families from a Fire whose fuel is Men and Stones, over which are (appointed) angels stern (and) severe, who flinch not (from executing) the Commands they receive from Allah, but do (precisely) what they are commanded.

(3) (The stern command will say): "Seize ye him, and bind ye him,

(4) 'And we pried into the secrets of heaven; but we found it filled with stern guards and flaming fires.