Hazrat Shaikh Moulana Muhammad Zakariyya (rahmatullahi ‘alaih) mentioned:

Let alone showing disrespect and having ill-feelings for the ‘Ulama and A’immah-e-mujtahideen, even disrespecting a normal person or Muslim and having ill-feelings for him is not permissible under any circumstances. Allah Ta’ala forbid, if one disrespects any of these seniors then, remember that one will lose everything. (Malfoozaate Hazrat Shaikh pg. 62)

Source: Ihyaauddeen.co.za