Matthew Henry on 1 Chronicles 12:1-22
We have here an account of those that appeared and acted as David's friends, upon the death of Saul, to bring about the revolution. All the forces he had, while he was persecuted, was but 600 men, who served for his guards; but, when the time had come that he must begin to act offensively, Providence brought in more to his assistance. Even while he kept himself close, because of Saul (Ch1 12:1), while he did not appear, to invite or encourage his friends and well-wishers to come in to him (not foreseeing that the death of Saul was so near), God was inclining and preparing them to come over to him with seasonable succours. Those that trust God to do his work for them in his own way and time s…
Read the whole note in the consoleJamieson-Fausset-Brown on 1 Chronicles 12:21
they helped David against the band--that is, the Amalekites who had pillaged Ziklag in David's absence. This military expedition was made by all his men (Sa1 30:9), who, as David's early helpers, are specially distinguished from those who are mentioned in the latter portion of the chapter.
Adam Clarke on 1 Chronicles 12:18
The spirit came upon Amasai - "The spirit of fortitude clothed Amasai, the chief of the mighty men; and he answered, For thy sake, O David, are we come, that we may be with thee, thou son of Jesse.
Prosperity be to thee by night and by day; and prosperity be to thy helpers; for the Word of the Lord is thy assistant." - T.
John Gill on 1 Chronicles 12:21
And they helped David against the band of the rovers,.... The Amalekites, who, while he was gone with the Philistines, had seized on Ziklag, and burnt it, and carried the women captive, with what spoil they could make; these coming to David thus opportunely, assisted him in his pursuit and defeat of them:
for they were all mighty men of valour, and were captains in the host; or army of David.
Keil & Delitzsch