Leviticus 10:13, Because it is due. In the days before coinage, a man’s wages were weighed out in silver bullion or bartering occurred. In the case of the Levites (including the priests), they were given a portion of the offerings and sacrifices as their wages for serving the people. It is often the attitude of those in congregations that ministers should serve the people for free—without pay, and they are therefore negligent in giving. This is contrary to the Torah, which commands the Israelites to remunerate the Levites for their services (see Lev 27:30, 32). YHVH even calls the tithe to his ministers “their inheritance” (Num 18:21, 26).
Although the Testimony of Yeshua doesn’t overtly promote the concept of tithing per se, it does teach the Torah principle of giving to the ministry. For example, Paul instructed the believers in Philippi about giving. He addresses the issue of supporting his ministry and that by their faithfulness in giving to him it was in effect giving an offering (or a sacrifice) to YHVH, and that the Philippians would be blessed for this (Phil 4:16–19). He goes on to say that we are to give to those who spiritually feed us (1 Tim 5:17–18). Paul backs up this assertion by quoting a Torah principle here.
Let the elders that rule well be counted worthy of double honour, especially they who labour in the word and doctrine. For the Scripture says, “You shalt not muzzle the ox that treads out the corn,” and, “The labourer is worthy of his reward.”
What’s more, the Scriptures tell us that great blessings from heaven accrue to those who tithe or give to YHVH’s spiritual work on earth (Mal 3:10–11).
To not give, according to the Scriptures is called “robbing Elohim” (Mal 3:8–9). Those who refuse to give financially bring a curse upon themselves (Mal 3:9). Paul rebukes the congregation in Corinth for not supporting him financially, and states that he has “robbed” other churches who did support him, thus forcing him to use their offerings to pay his ministry expenses in Corinth (2 Cor 11:8–9). Corinth was not the only stingy congregation in the first century. The problem seemed to be widespread then (Phil 4:15) as it is today.