The word(s) "solemn" appears 3 time(s) in 3 verse(s) in Quran in Saheeh International translation.

(1) And how could you take it while you have gone in unto each other and they have taken from you a solemn covenant?

(2) And We raised over them the mount for [refusal of] their covenant; and We said to them, "Enter the gate bowing humbly", and We said to them, "Do not transgress on the sabbath", and We took from them a solemn covenant.

(3) And [mention, O Muhammad], when We took from the prophets their covenant and from you and from Noah and Abraham and Moses and Jesus, the son of Mary; and We took from them a solemn covenant.