Matters pertaining to Deen must be accepted without the slightest doubt.

Allah, the Exalted, says: And whatsoever the Messenger (Muhammad PBUH) gives you, take it, and whatsoever he forbids you, abstain (from it) and fear Allah. Verily, Allah is severe in punishment. (59:7)

One must follow the guidance of the Prophet PBUH in these matters, and should not make 'ijtihaad' (i.e. to exert his effort to reach a ruling) in an issue that does not allow such.