In 1 Samuel 13 and 1 Samuel 15, for which act of Saul's disobedience did God take away the kingdom?

Question

After offering an unsanctioned sacrifice Saul is told the kingdom has been taken away from him & has been given to a man after God's own heart

1 Samuel 13 NASB

8 Now he waited seven days, according to the appointed time set by Samuel, but Samuel did not come to Gilgal; and the people were scattering from him. 9 So Saul said, “Bring to me the burnt offering and the peace offerings.” And he offered the burnt offering. 13 Samuel said to Saul, “You have acted foolishly; you have not kept the commandment of the Lord your God, which He commanded you, for now the Lord would have established your kingdom [f]over Israel forever. 14 But now your kingdom shall not endure. The Lord has sought out for Himself a man after His own heart, and the Lord has appointed him as ruler over His people, because you have not kept what the Lord commanded you.”

Again later Saul is ordered to destroy the Amalekites but he disobeys the instructions & again he is told that the kingdom has been taken away & given to his neighbour.

1 Samuel 15 NASB

20 Then Saul said to Samuel, “I did obey the voice of the Lord, and went on the [k]mission on which the Lord sent me, and have brought back Agag the king of Amalek, and have utterly destroyed the Amalekites. 21 But the people took some of the spoil, sheep and oxen, the choicest of the things devoted to destruction, to sacrifice to the Lord your God at Gilgal.” 28 So Samuel said to him, “The Lord has torn the kingdom of Israel from you today and has given it to your neighbor, who is better than you.

The above texts contain two acts of disobedience with similar admonishing,

Could it be God had already taken the kingdom away from Saul regardless of his second disobedience.

Which of the two actions caused the taking away of his kingdom?

1) Unsanctioned offering

2) Destruction of the Amalekites

Answer 1

There were more than two sins committed by Saul here. (It is possible that 1 Sam 13:3-15 should be either part of 1 Sam 15 or a later narrative because it is incomplete.)

1. Not encouraging the soldiers during his wait for Samuel and not maintaining trust in divine power as evidenced by his impatience in not waiting for Samuel
2. Offering an unsanctioned sacrifice
3. Incomplete destruction of the Amalekites - they spared the best of the livestock and spared the king, Agag, as a trophy of war (a common practice at the time)
4. Displaying an extended and deep-seated self-justifying spirit when rebuked by Samuel
5. Wanting to use others' animals (ie, spoils of war) for sacrifice - David later correctly observed that he would "not offer to the Lord that which cost him nothing" (2 Sam 24:24).

In summary, King Saul was more interested in self aggrandisement (see 1 Sam 15:12) and so could not fully trust in God's power.