Commentary on the Bible, by Adam Clarke, [1831], at sacred-texts.com
1 Chronicles Chapter 12
The different persons, captains, etc., who joined themselves to David at Ziklag, vv. 1-22. Those who joined him at Hebron, out of the different tribes; Judah, Simeon, Levi, the house of Aaron, Benjamin, Ephraim, Manasseh, Issachar, Zebulun, Naphtali, Dan, Asher, Reuben, etc., to the amount of a hundred and twenty thousand, Ch1 12:23-37. Their unanimity, and the provisions they brought for his support, Ch1 12:38-40.
Came to David to Ziklag - Achish, king of Gath, had given Ziklag to David, as a safe retreat from the wrath of Saul.
And were as swift as the roes - That swiftness was considered to be a grand accomplishment in a warrior, appears from all ancient writings which treat of military affairs.
In the first month - Perhaps this was the month Nisan, which answers to a part of our March and April. This was probably before the snows on the mountains were melted, just as Jordan began to overflow its banks; or if we allow that it had already overflowed its banks, it made their attempt more hazardous, and afforded additional proof of their heroism.
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.
Like the host of God - "That is, a very numerous army; like the army of the angel of God." - T.
And came to David to Hebron - That is, after the death of Ish-bosheth, Saul's son. See Sa2 4:5.
Jehoiada was the leader of the Aaronites - Abiathar was then high priest, and Jehoiada captain over the warriors of the house of Aaron.
Children of Issachar - According to the Targum they were all astronomers and astrologers: "and the sons of Issachar, who had understanding to know the times, and were skilled in fixing the beginnings of years, the commencement of months, and the intercalation of months and years; skillful in the changes of the moon, and in fixing the lunar solemnities to their proper times; skillful also in the doctrine of the solar periods; astrologers in signs and stars, that they might show Israel what to do; and their teachers were two hundred chiefs of the Sanhedrin: and all their brethren excelled in the words of the law, and were endued with wisdom, and were obedient to their command." - T. It appears that in their wisdom, experience, and skill, their brethren had the fullest confidence; and nothing was done but by their direction and advice.
They were with David three days - These were the deputies of the different people mentioned here: it is not possible that all the thousands mentioned above could have feasted with David for three days; and yet it appears there was even of these a great number, for the men of Issachar, Zebulun, and Naphtali, who were nearest to this place of rendezvous, had brought all the necessaries for such a feast. From the whole it appears most evident that the great majority of the tribes of Israel wished to see the kingdom confirmed in the hands of David; nor was there ever in any country a man more worthy of the public choice. As a statesman, warrior, hero, poet, and divine, he stands unrivalled in the annals of the world: by him alone were the Israelites raised to a pitch of the highest splendor; and their name became a terror to their enemies, and a praise in the earth. But, alas, how are the mighty now fallen!