Deuteronomy 26:13
Then thou shalt say before the Lord thy God, I have brought away the hallowed things out of mine house, and also have given them unto the Levite, and unto the stranger, to the fatherless, and to the widow, according to all thy commandments which thou hast commanded me: I have not transgressed thy commandments, neither have I forgotten them:
Cross-references
Deuteronomy 26:12 describes the act of giving the tithe to the poor; verse 13 is the declaration of having done so.
Deuteronomy 14:29 commands giving tithes to the Levite, stranger, fatherless, and widow—the same groups mentioned in the declaration of obedience here.
Deuteronomy 24:19-21 commands leaving gleanings for the poor, reinforcing the same ethic of caring for the needy that underlies the tithe declaration.
Job 31:16-20 also boasts of caring for the poor and not eating alone—mirroring the claim of obedience to God's commands for the needy.
Numbers 18:8 describes the sacred contributions given to priests, providing the background for the tithe system referenced here.
1 John 3:17-22 links assurance before God to loving in deed and truth, paralleling the clear conscience from obeying commands here.