And it came to pass the next day, that the evil spirit from God came upon Saul, and he prophesied in the midst of the house: and David played with his hand, as at other times: and there was a javelin in Saul's hand.
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It was also through a wicked angel that the transgressor was tempted in the account of the book of Kings [Samuel], where it says “The evil spirit from God came upon Saul.” Just men, too, like Job and the apostle Paul and others of that kind were tried by the devil. It is clear that all created things are subject to the discretion or command of the Creator. - "Exposition of the Psalms 77.49"
Prophesied. Acted the prophet in a mad manner, (Challoner) like an enthusiast, (Calmet; 2 Kings ix. 11.) or one possessed by the devil, as the Sybil was agitated by Apollo. Et rabie fera corda tument. (Virgil, Æneid vi.) To alleviate his distress, David took up his harp. (Haydock)
Spear. With this weapon he was generally armed, chap. xix. 10., and xxvi. 7. "It was used as a diadem formerly, and the ancients adored spears as gods. "(Justin. xliii.)