Hastings' Dictionary of the Bible (1898)
BEARD. Among the Jews much attention was paid to the beard. To show any contempt toward it by Fig. 1. Egyptian Beards. ) Fig. 2. Beards of Assyrian, and other Nations. ) plucking it or touching it, except from respect or courtesy, was esteemed a gross insult, while to kiss it respectfully and affectionately was regarded as a signal mark of friendship. Tearing out the beard, cutting it entirely off, and neglecting to trim and dress it were all expressions of deep mourning. Ezr 9:3; Isa 15:2; Jer 41:5 and Jer 48:37.
The Arabs and Orientals generally at this day cherish great respect for the beard. " We are told of an Arab who was wounded in the jaw, and chose to hazard his life rather than to have his beard cut off that the surgeon might examine the wound. Hence the keenness of the insult offered to David's ambassadors. 2 Sam 10:4-5. The Egyptians were accustomed to shave except when mourning, the direct opposite to the Jewish custom, but they wore false beards, made of plaited hair and graduated according to rank.
The prohibition, Lev 19:27, against marring the "corners of the beard" refers probably to the Arabian custom of shaving off that portion of the beard upon the cheeks on a line with the ears.