The word(s) "solemn" appears 3 time(s) in 2 verse(s) in Quran in Mohsin Khan translation.

(1) He [Ya'qub (Jacob)] said: "I will not send him with you until you swear a solemn oath to me in Allah's Name, that you will bring him back to me unless you are yourselves surrounded (by enemies)," And when they had sworn their solemn oath, he said: "Allah is the Witness to what we have said."

(2) Those who offer their Salat (prayers) with all solemnity and full submissiveness.