Then some of the [b]men of Benjamin and Judah came to the stronghold to David. David went out to meet them and said to them, “If you have come peacefully to me to help me, my heart shall be united with you; but if you have come to betray me to my adversaries, since there is no violence or wrong in my hands, may the God of our fathers look on [what you are doing] and punish [you].” Then the [Holy] Spirit came on Amasai, who was chief of the thirty, and he said,
“We are yours, O David,
And with you, O son of Jesse!
Peace, peace be to you,
And peace be to him who helps you;
For your God helps you.
Then David accepted and received them and made them officers of his troops. 1 Chronicles 12:16-18
Amasai is probably the same as Amasa. He would have been David’s nephew by his sister, Abigail.
The Spirit was revealed when Amasai spoke with boldness, courage and blessing and gave him the words to speak as such. The result of this temporary empowerment by the Holy Spirit – David believed the words and was assured that the Benjamites and Judahites were loyal to him – so much so that he even made them leaders among his men.
How would you describe the Spirit of God coming over you? Would you talk about being filled? Would you use words about a deep, inner experience? Would you describe the occurrence with emotional overtones or transcendental hyperbole? You might find it startling when you discover that the Bible doesn’t use any of this sort of language in its description of the Spirit coming upon Amasai. In fact, the biblical description is a lot more like Paul’s statements in Ephesians 6:13. The Hebrew verb here is lavash. It means “to wear, to dress, to put on clothing.” When the Spirit encountered Amasai, it was like Amasai put on new clothes, a new set of armor. He was “covered” in the Spirit. Skip Moen
Some modern preachers have suggested that to be filled with the Spirit means to be under the Spirit’s control, which means that He will make you nice and sweet and godly. Clearly one aspect of the Spirit’s work in our lives is to do just that, but when we read of being clothed with the Spirit, it is more than us simply becoming nice people. The Spirit’s anointing is to empower us to fulfill God’s calling by God’ power. When Peter got up to preach in Acts, we read, “Then Peter, filled with the Holy Spirit, said to them…” This does not mean Peter was filled with the Spirit, rose up, and became a nice guy. It clearly declares the anointed apostle rose up in the power of the Holy Spirit and preached the gospel with a fluency and force that went beyond human ability. – Dennis Pollack
I believe one reason the Spirit of God came on different people – so the people of God were able to recognize their enemies and their friends. David did not know this person was a friend until they began to speak the words the Lord gave them.