'New moon' in the Bible

And David said to Jonathan, Behold, tomorrow is the new moon, and I should not fail to sit with the king to eat. But let me go that I may hide myself in the field to the third day at evening.

Then Jonathan said to him, Tomorrow is the new moon, and thou will be missed because thy seat will be empty.

So David hid himself in the field. And when the new moon came, the king sat down to eat food.

And it came to pass on the morrow after the new moon, [which was] the second [day], that David's place was empty. And Saul said to Jonathan his son, Why has the son of Jesse not come in to the food, neither yesterday, nor today?