“Are you well, my brother?” Joab asked Amasa. And with his right hand Joab grabbed Amasa by the beard to kiss him.
We have here Amasa's fall just as he began to rise. He was nephew to David (Sa2 17:25), had been Absalom's general and commander-in-chief of his rebellious army, but, that being routed, he came over into David's interest, upon a promise that he should be general of his forces instead of Joab.
Commenting on 2 Samuel 20:4-13
And Joab said to Amasa,.... In a friendly manner, with all the air of pleasantry and good humour: art thou in health, my brother? this looked like a friendly salutation to ask of his health, and wish him it, and a loving appellation to call him brother; though they were near of kin, sisters' children, and so own cousins; thus he addressed him, to cover...
took Amasa by the beard with the right hand to kiss him--This act, common with two friends on meeting when one of them returns from a journey, indicates respect as well as kindliness, and the performance of it evinced the deep hypocrisy of Joab, who thereby put Amasa off his guard.