Imam al-Shafi'i (may Allah have mercy on him) said: "Everyone who made an interpretation (of some evidence) and then committed an act while considering it lawful, whether it carries a prescribed punishment (hadd) or not, his testimony is not rejected because of it. Do you not see that among those from whom (knowledge of) the religion was taken, and who were set up as beacons (of knowledge) in the lands, are some who considered temporary marriage (mut'ah) lawful; some who consider (selling) one dinar for ten dinars hand to hand lawful; some who, by interpretation, considered shedding blood lawful; some who, by interpretation, drank every intoxicant other than wine (khamr); some who declared lawful approaching women in their rear; and some who declared lawful sales that are unlawful in the view of others? So since these people, despite what I have described, are trustworthy in their religion and well regarded by those who know them, and their interpretations in which they erred have been left (without being held against them), and they were not removed (from uprightness) by that great error since it came from them on the basis of considering it lawful, then all the people of desires (innovators) are of this same rank."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / Q20916