2 Samuel 20:9

“And Joab said to Amasa, etc.] 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 his design: and Joab took Amasa by the beard with his right hand to kiss him: as was usual for the eastern people to do when they addressed and saluted one another in an affectionate way, and as the Turks and Arabs do to this day, as travellers relate. Barthius f338 has collected passages from the Greek poets, which show it to be a custom,…”

“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. No wonder, then, that while this act of friendly gratulation after long absence occupied Amasa's attention, he did not perceive the sword that was in Joab's left hand. The action of Joab was indeed a high compliment, but neither suspicious nor unusual and to this compliment, Amasa paying attention and no doubt returning it with suitable politeness, he could little expect the fatal event that Joab's perfidy…”

“Beard - As the manner of ancient times was, when they saluted one another. 2 Kings (2 Samuel) 20:10”

“20:9 to kiss him: This affectionate greeting was not always genuine (cp. 14:33).”

“Art thou: Psa 55:21; Pro 26:24-26; Mic 7:2 took Amasa: Thevenot says, that among the Turks it is a great affront to take one by the beard, unless it be to kiss him, in which case they often do it. D'Arvieux, describing an assembly of Arab emirs at an entertainment, says, "After the usual civilities, caresses, kissings of the beard, and of the hand, which every one gave and received according to his rank and dignity, they sat down upon mats." The doing this by the Arab emirs corresponds with the conduct of Joab, and illustrates this horrid assassination. to kiss him: Mat 26:48, Mat 26:49; Luk 22:47, Luk 22:48 2 Kings (2 Samuel) 20:10”