[مَعْنًى] Giving fatwa is a communal duty (farḍ kifāya, فرض كفاية). It becomes a personal duty when the muftī is the only one available, or the need is urgent. He must refuse to answer when he does not know the ruling, when the answer would cause clear harm, or when the case turns on a local custom he does not know. Answering from ignorance is a sin.
📘 التقي العثماني، أصول الإفتاء وآدابه، ص ٣٣٤–٣٣٩
[مَعْنًى] If the muftī finds his fatwa was wrong, he takes it back openly. What happens to action already taken depends on the error. If the old fatwa broke a clear, decisive proof, the action is undone. If it was a matter of ijtihād, the action stands, because one ijtihād does not cancel another. He should tell the questioner of the change.
📘 التقي العثماني، أصول الإفتاء وآدابه، ص ٣٤٥–٣٤٨
[مَعْنًى] In the Ḥanafī view (Ibn Nujaym, al-Baḥr al-Rāʾiq), a qualified muftī who errs owes no compensation (ḍamān, ضمان), even if the questioner acted on the fatwa and lost property. There was no force; the questioner chose to act. Some non-Ḥanafīs hold the qualified muftī liable.
📘 التقي العثماني، أصول الإفتاء وآدابه، ص ٣٤٩
[النَّصُّ] فَيَجِبُ عَلَى الْمُفْتِي أَنْ يُمَيِّزَ بَيْنَهُمَا، وَيُوقِفَ فِكْرَهُ عَلَى الْوَاقِعَاتِ الْمُؤَثِّرَةِ فَقَطْ
[مَعْنًى] Step one: picture the case exactly (taṣawwur, تصور). Tell the facts that change the ruling from the side facts that do not. Verify the questioner's facts, ask follow-up questions, and where needed read the real contract or law and consult experts. Step two: place the case under the right ruling (al-takyīf al-sharʿī, التكييف الشرعي). Then answer.
📘 التقي العثماني، أصول الإفتاء وآدابه، ص ٣٥٢–٣٥٣
[مَعْنًى] State the ruling first, in plain words the questioner can follow, then the proof. Leave no gap between the question and the answer, so nothing can be inserted. Use "ḥarām" (حرام) only for what a decisive proof forbids; for a disputed matter say "not allowed" (غير جائز). Before endorsing another muftī's written fatwa, check that he is qualified.
📘 التقي العثماني، أصول الإفتاء وآدابه، ص ٣٧٤