should not fail to sit. Septuagint reads "shall not sit". unto the third day at even. Septuagint reads "until the evening". Compare 1 Samuel 20:12.
Related Commentaries of 1 Samuel 20:5
1 Samuel 20:5
5 And David said unto Jonathan, Behold, to morrow is the new moon, and I should not fail to sit with the king at meat: but let me go, that I may hide myself in the field unto the third day at even.