The Prophet ﷺ used to trim his beard from its width and its length.
حدثنا هناد حدثنا عمر بن هارون عن أسامة بن زيد
أن النبي ﷺ كان يأخذ من لحيته من عرضها وطولها
No references are available.
[Its chain of transmission is extremely daif] Ibn Adi reported it, 5/1689, from the hadith of Umar bin Harun through this route, and he is matruk (abandoned) though he was a hafiz (Taqrib).The hadith that the Prophet ﷺ set up the catapult, etc., its chain of transmission is extremely daif, along with being mursal.