Jacob did not tithe, he vowed to tithe but was not fulfilled in his lifetime.
“Then Jacob made a vow, saying, “If God will be with me, and keep me in this way that I am going, and give me bread to eat and clothing to put on, so that I come back to my father’s house in peace, then the LORD shall be my God. And this stone which I have set as a pillar shall be God’s house, and of all that You give me I will surely give a tenth to You.”Genesis 28:20-22 NKJV
Since promise to God should not be broken, God asked what had been vowed to Him through Jacob or Israel as people.
Part of Jacob’s vow was to give a tenth of what will God give him and God gives the land of Canaan therefore, a tenth of the land was returned for the promise to be fulfilled.
Abraham did tithe but was not commanded to do so. He tithed without any rule of what and to whom the tithe shall be given.
Any act of giving 10% to whoever and whatever is called tithing if based before the law. There are no rules to bound, where, whom, what is tithing since there is no law about it before the law. So, if I give 10% to the needy and have faith that by doing so, I’m giving to God, I’m basically tithing the same as Abraham which was by faith or believing that you are giving to God.
Also, you cannot really follow how Abraham tithed since he gave it to someone who was described in Heb. 7: 1-3 to be of no beginning, nor end of life. I’m pretty sure that no man today lives forever.