Musannaf Ibn Abi Shaybah 34914 — What they said on wearing marks

Ibn Awn (may Allah have mercy on him) said that Umayr bin Ishaq (may Allah have mercy on him) said: On the day of the Battle of Badr, it was said to the Companions (may Allah be pleased with them): "Make a mark and sign for yourselves, for the angels have marked themselves as well." He said: The first time wool was made a mark was on that day.