Is touching the Mushaf while predominantly uncertain about the emission of discharge, the source of which is unknown, a major sin?

When in doubt about the discharge of secretions from the urinary exit, no judgment is made based on that. Ablution is not invalidated merely by doubt, even if there is a strong presumption that secretions have exited. The original state is the continuation of purity until there is absolute certainty of invalidation, as explained by Al-Nawawi, citing the hadith: "He should not leave (his prayer) until he hears a sound or finds a smell." If moisture is found, it is attributed to the earliest time it could have occurred. There is no sin in touching the Mus'haf (Qur'an) when in doubt about impurity, due to the original state of purity remaining. If impurity is certain after touching it, there is no sin for not intentionally touching the Mus'haf while impure, in accordance with His, the Almighty's, saying: "And there is no blame upon you for that in which you have erred, but [there is blame for] what your hearts intended."