No one was to help the Levites on the threat of death!
This is quite surprising. Surely as Christians we ought to help everyone. Yet here we are told that this particular task was something the Levites had to do on their own.
There are times not to help. We shouldn't help if we are only doing so to make ourselves feel good. We shouldn't help if we are making someone depend on us and they ought to be taking responsibility for themselves. We shouldn't help if this is a task God has given solely to someone else.
Paul teaches the Galatians, "Carry each other’s burdens, and in this way you will fulfill the law of Christ" but then adds, "for each one should carry their own load" (Galatians 6-2, 5).
There is a time to carry another's burden when they are weighted down and unable to continue but there is also a time when we carry our own load, we manage our own lighter responsibilities.
In the same passage Paul also says, "Each one should test their own actions" (v. 4). What's our motive for helping? Are we responding to God's prompting? Are we seeking something in return? Even if we are only looking for gratitude, our desire may be to put someone in our debt. It is only God who knows our true motive. If in doubt we can always ask him to show us.
We don't always do people a favour by helping. It requires good discernment to know when to help and when to hold back.