Lest I mar mine own inheritance; either, first, Because having no children of his own, he might have one, and but one, son by Ruth, who, though he should carry away his inheritance, yet should not bear his name, but the name of Ruth's husband; and so by preserving another man's name, he should lose his own. Or, secondly, Because as his inheritance would be but very little increased by this marriage, so it might be much diminished by being divided amongst his many children, which he possibly had already, and might probably have more by Ruth. Redeem thou my right, which I freely renounce and resign to thee.
Related Commentaries of Ruth 4:6
Ruth 4:6
6 And the kinsman said, I cannot redeem it for myself, lest I mar mine own inheritance: redeem thou my right to thyself; for I cannot redeem it.