1 Samuel 14:35

35. The same was the first altar that he built Literally, It he began to build an altar to Jehovah. Compare margin. This, means, according to Grotius, that Saul commenced the building of the altar by laying the first stone himself. Hervey thinks he began to build an altar, but, in his haste to pursue the Philistines, did not finish it. But the previous sentence states that he did build the altar, and the previous verse implies that sacrifices were offered on it. The more probable meaning is the one conveyed by our version this was the first altar, or the beginning of Saul’s altar building. The altar of the burnt offerings at Gilgal (1 Samuel 13:9) had been erected by others. It is very supposable and probable that Saul built many other altars to Jehovah.