Could you show that from scripture?
Genesis 14:20 And blessed be the most high God, which hath delivered thine enemies into thy hand. And he gave him tithes of all.
Leviticus 27:30 And all the tithe of the land, whether of the seed of the land, or of the fruit of the tree, is the Lord's: it is holy unto the Lord.
Leviticus 27:31 And if a man will at all redeem ought of his tithes, he shall add thereto the fifth part thereof.
Leviticus 27:32 And concerning the tithe of the herd, or of the flock, even of whatsoever passeth under the rod, the tenth shall be holy unto the Lord.
Numbers 18:24 But the tithes of the children of Israel, which they offer as an heave offering unto the Lord, I have given to the Levites to inherit: therefore I have said unto them, Among the children of Israel they shall have no inheritance.
Numbers 18:26 Thus speak unto the Levites, and say unto them, When ye take of the children of Israel the tithes which I have given you from them for your inheritance, then ye shall offer up an heave offering of it for the Lord, even a tenth part of the tithe.
Numbers 18:28 Thus ye also shall offer an heave offering unto the Lord of all your tithes, which ye receive of the children of Israel; and ye shall give thereof the Lord'S heave offering to Aaron the priest.
Deuteronomy 12:6 And thither ye shall bring your burnt offerings, and your sacrifices, and your tithes, and heave offerings of your hand, and your vows, and your freewill offerings, and the firstlings of your herds and of your flocks:
Deuteronomy 12:11 Then there shall be a place which the Lord your God shall choose to cause his name to dwell there; thither shall ye bring all that I command you; your burnt offerings, and your sacrifices, your tithes, and the heave offering of your hand, and all your choice vows which ye vow unto the Lord:
Deuteronomy 12:17 Thou mayest not eat within thy gates the tithe of thy corn, or of thy wine, or of thy oil, or the firstlings of thy herds or of thy flock, nor any of thy vows which thou vowest, nor thy freewill offerings, or heave offering of thine hand:
Deuteronomy 14:22 Thou shalt truly tithe all the increase of thy seed, that the field bringeth forth year by year.
Deuteronomy 14:23 And thou shalt eat before the Lord thy God, in the place which he shall choose to place his name there, the tithe of thy corn, of thy wine, and of thine oil, and the firstlings of thy herds and of thy flocks; that thou mayest learn to fear the Lord thy God always.
Deuteronomy 14:28 At the end of three years thou shalt bring forth all the tithe of thine increase the same year, and shalt lay it up within thy gates:
Deuteronomy 26:12 When thou hast made an end of tithing all the tithes of thine increase the third year, which is the year of tithing, and hast given it unto the Levite, the stranger, the fatherless, and the widow, that they may eat within thy gates, and be filled;
2 Chronicles 31:5 And as soon as the commandment came abroad, the children of Israel brought in abundance the firstfruits of corn, wine, and oil, and honey, and of all the increase of the field; and the tithe of all things brought they in abundantly.
2 Chronicles 31:6 And concerning the children of Israel and Judah, that dwelt in the cities of Judah, they also brought in the tithe of oxen and sheep, and the tithe of holy things which were consecrated unto the Lord their God, and laid them by heaps.
2 Chronicles 31:12 And brought in the offerings and the tithes and the dedicated things faithfully: over which Cononiah the Levite was ruler, and Shimei his brother was the next.
Nehemiah 10:37 And that we should bring the firstfruits of our dough, and our offerings, and the fruit of all manner of trees, of wine and of oil, unto the priests, to the chambers of the house of our God; and the tithes of our ground unto the Levites, that the same Levites might have the tithes in all the cities of our tillage.
Nehemiah 10:38 And the priest the son of Aaron shall be with the Levites, when the Levites take tithes: and the Levites shall bring up the tithe of the tithes unto the house of our God, to the chambers, into the treasure house.
Nehemiah 12:44 And at that time were some appointed over the chambers for the treasures, for the offerings, for the firstfruits, and for the tithes, to gather into them out of the fields of the cities the portions of the law for the priests and Levites: for Judah rejoiced for the priests and for the Levites that waited.
Nehemiah 13:5 And he had prepared for him a great chamber, where aforetime they laid the meat offerings, the frankincense, and the vessels, and the tithes of the corn, the new wine, and the oil, which was commanded to be given to the Levites, and the singers, and the porters; and the offerings of the priests.
Nehemiah 13:12 Then brought all Judah the tithe of the corn and the new wine and the oil unto the treasuries.
Amos 4:4 Come to Bethel, and transgress; at Gilgal multiply transgression; and bring your sacrifices every morning, and your tithes after three years:
Malachi 3:8 Will a man rob God? Yet ye have robbed me. But ye say, Wherein have we robbed thee? In tithes and offerings.
Malachi 3:10 Bring ye all the tithes into the storehouse, that there may be meat in mine house, and prove me now herewith, saith the Lord of hosts, if I will not open you the windows of heaven, and pour you out a blessing, that there shall not be room enough to receive it.
Matthew 23:23 Woe unto you, scribes and Pharisees, hypocrites! for ye pay tithe of mint and anise and cummin, and have omitted the weightier matters of the law, judgment, mercy, and faith: these ought ye to have done, and not to leave the other undone.
Luke 11:42 But woe unto you, Pharisees! for ye tithe mint and rue and all manner of herbs, and pass over judgment and the love of God: these ought ye to have done, and not to leave the other undone.
Luke 18:12 I fast twice in the week, I give tithes of all that I possess.
Hebrews 7:5 And verily they that are of the sons of Levi, who receive the office of the priesthood, have a commandment to take tithes of the people according to the law, that is, of their brethren, though they come out of the loins of Abraham:
Hebrews 7:6 But he whose descent is not counted from them received tithes of Abraham, and blessed him that had the promises.
Hebrews 7:8 And here men that die receive tithes; but there he receiveth them, of whom it is witnessed that he liveth.
Hebrews 7:9 And as I may so say, Levi also, who receiveth tithes, payed tithes in Abraham.
Although there is no such statement in scripture such as, "the tithe is the minimum" a quick look at the above scriptures does indicate that the tithe was the portion expected.
Is a lesser amount ever indicated? I am not aware of such a scripture,
But I do see in
Malachi 3:8 Will a man rob God? Yet ye have robbed me. But ye say, Wherein have we robbed thee? In tithes and offerings.
the clear indication that not tithe and offering is called robbery.
Robbing God, it is not referred to as robbing your denomination or your church leaders but robbing God.
Also noteworthy is the word "offering" that indicates something beyond the tithe
Granted that Malachi was under the law as were the people God revealed his will to by Malachi
But we do see Abraham give a tithe and that was many years before the law required it
Abraham is referred to as the father of all that believe. Tithing is believing