דברי הימים א, פרק כ״א, פסוק ל׳

King David finds himself in a critical situation, commanded by God to offer a sacrifice but physically unable to reach the proper location. A deep, paralyzing fear prevents him from making the necessary journey. The primary approach among commentators is that David originally needed to travel to the great altar, which was located in Gibeon at the time. However, he was completely terrified and unable to leave the city limits. A gripping dread took hold of him, draining his physical strength [מצודת דוד ומצודת ציון]. This intense panic was caused by the threatening sight of an angel standing outside with a drawn sword [ביאור שטיינזלץ].

Because this fear kept him from traveling to the original altar in Gibeon, David acted on the instructions of a prophet. He built a new altar at the threshing floor of Ornan and offered his sacrifices of atonement right where he was [רש י ומצודת דוד].

The historical background of this moment explains why the altar was so far away. Previously, David had brought the Ark of the Covenant to Jerusalem so it would be close to him. However, he was not entirely certain yet if Jerusalem was meant to be its permanent home. As a result, the Ark was kept in a temporary tent in Jerusalem, while the original sacred vessels remained in Gibeon. It was this physical distance between the two locations that David was simply too afraid to cross while the armed angel stood in his path [ביאור שטיינזלץ].