The word(s) "soundness" appears 5 time(s) in 5 verse(s) in Quran in Saheeh International translation.

(1) Or do you intend to ask your Messenger as Moses was asked before? And whoever exchanges faith for disbelief has certainly strayed from the soundness of the way.

(2) And Allah had already taken a covenant from the Children of Israel, and We delegated from among them twelve leaders. And Allah said, "I am with you. If you establish prayer and give zakah and believe in My messengers and support them and loan Allah a goodly loan, I will surely remove from you your misdeeds and admit you to gardens beneath which rivers flow. But whoever of you disbelieves after that has certainly strayed from the soundness of the way."

(3) Say, "O People of the Scripture, do not exceed limits in your religion beyond the truth and do not follow the inclinations of a people who had gone astray before and misled many and have strayed from the soundness of the way."

(4) One of soundness. And he rose to [his] true form

(5) O you who have believed, do not take My enemies and your enemies as allies, extending to them affection while they have disbelieved in what came to you of the truth, having driven out the Prophet and yourselves [only] because you believe in Allah, your Lord. If you have come out for jihad in My cause and seeking means to My approval, [take them not as friends]. You confide to them affection, but I am most knowing of what you have concealed and what you have declared. And whoever does it among you has certainly strayed from the soundness of the way.