ירמיהו, פרק י״ג, פסוק ב׳

Following a specific divine command, Jeremiah acquires and wears a linen belt. He acts with absolute precision, paying close attention to every single detail of God's instruction. Rather than simply finding any belt, he personally goes out to purchase it, ensures it is the exact right size to fit him, and carefully checks that it is made specifically of linen. Furthermore, he does not just put the belt on for a brief moment to fulfill the requirement. Instead, he ties it securely around his waist and wears it constantly as a permanent part of his daily clothing [מלבי״ם].