Contradiction with 1 Samuel 9:2
1 Samuel 9:2 describes Saul as a choice and handsome young man, indicating he stood out among the people, whereas 1 Samuel 10:21 suggests a random selection process without mention of Saul's distinguishing features.
1 Samuel 9:2: And he had a son, whose name [was] Saul, a choice young man, and a goodly: and [there was] not among the children of Israel a goodlier person than he: from his shoulders and upward [he was] higher than any of the people.
Contradiction with Acts 1:24-26
In Acts 1:24-26, the selection of Matthias as an apostle involved prayer and casting lots, implying divine intervention or confirmation, while 1 Samuel 10:21 describes the selection of Saul through a casting of lots without explicit mention of seeking divine guidance at that moment.
Acts 1:24-26: And they prayed, and said, Thou, Lord, which knowest the hearts of all [men], shew whether of these two thou hast chosen,
Contradiction with 1 Samuel 8:7
In 1 Samuel 8:7, the people rejected God as their king, but 1 Samuel 10:21 indicates God’s choice of Saul as king through a lot, suggesting divine approval of kingship despite the earlier rejection.
1 Samuel 8:7: And the LORD said unto Samuel, Hearken unto the voice of the people in all that they say unto thee: for they have not rejected thee, but they have rejected me, that I should not reign over them.