This particular narrative points out a few but very important aspects of worship.
1. It is God who mandates specific regulations on how the people should approach him. That is to say, worship is not carried out whenever, however, wherever, and whoever the people want. Rather, it is God who sets the policy and procedures, not man. That is to say, it not only matters who we worship, but also how we worship.
2. God wants his people to actually spend some time preparing to meet their God (vv. 10-11). In fact, God commanded the people two days of special preparation. Such preparation was both inward and outward preparations. Inward preparations included Scriptural meditations, prayer, singing, confession of sins, repentance, and so on. The outward preparations included getting some adequate physical rest, sleep, personal hygiene, and even taking time to have proper attire for the occasion.
3. God should be approached with fear and reverence. The fact that God had set up bounds indicates that there are limitations, such as what is permissible and what is not permissible, and that there is a consequence if those God-given bounds are ignored, namely, a death penalty (vv. 12-13a).
4. It is God who calls the people to come to him, including when and where (v. 13b). Not only God calls us to salvation, namely, with his effectual call, but also it is God who calls us to a sacrificial and holy worship. For us at Sovereign Grace Bible Church, I usually remind the congregation with a biblical text during the “Call to Worship” that it is God who officially summons us by his word to worship him. It is a wonderful reminder at the onset of worship service that God chose us, we didn’t choose him; he sought us, we didn’t seek him; he first loved us, we didn’t first love God; and he first called us, we didn’t first call him.