1 Corinthians 16
1Now concerning[a](A) the collection for the saints: as I directed the churches of Galatia, so you also are to do. 2On(B) the first day of every week, each of you is to put something aside and store it up,(C) as he may prosper,(D) so that there will be no collecting when I come.
As I understand it, the Old Testament tithe system (e.g. Levitical Law) was very specific but that was civil law given to Israel and as the Westminster Confession says, "expired with the nation and is not binding on any other except as the general equity requires."
This was an example of collecting on the Lord's Day but not a "law."