Study the inspired writings
When one disobeys God, he has done foolishly, because in the long run he will only hurt himself. God’s commands are not arbitrary, but are uttered with man’s best interests in mind. Although Samuel instructed Saul to wait seven days since Samuel was Yahweh’s prophet, it was the commandment of the Lord. God usually revealed his will through his inspired messengers, rather than through some direct, awe-inspiring method, in both OT and NT times. If one wishes to know his will, he should study the inspired writings which these messengers have left (cf. Eph. 3:3-4; 2 Tim. 2:2; 3:14-17).
—J.T. Willis, First and Second Samuel, 138.