It happened on the next day, that an evil spirit from God came mightily on Saul, and he prophesied in the midst of the house: and David played with his hand, as he did day by day. Saul had his spear in his hand;
But let us examine the original more closely: it is said that Saul prophesied in the midst of his house, that is, he prayed in his family, while David was playing on the harp; and then suddenly threw his javelin, intending to have killed David. Let it be observed that the word ויתנבא vaiyithnabbe is the third person singular of the future hithpael; the sign of which is not only to do an action on or for one's self, but also to feign or pretend to do it. The meaning seems to be, SAUL pretended to be praying in his family, the better to conceal his murderous intentions, and render David unsuspicious; who was, probably, at this time performing the musical part of the family worship. This view of the subject makes the whole case natural and plain.