"من سئل عن علم فكتمه ألجم يوم القيامة بلجام من نار"
Abu Hurairah (May Allah be pleased with him) reported: The Messenger of Allah (ﷺ) said, "He who is asked about knowledge (of religion) and conceals it, will be bridled with a bridle of fire on the Day of Resurrection." [Abu Dawud and At- Tirmidhi] .