Remove not the old landmark - See Proverbs 22:28 (note).
Enter not into the fields of the fatherless - Take nothing that belongs to an orphan. The heaviest curse of God will fall upon them that do so.

Remove not the old landmark,.... See Gill on Proverbs 22:28;
and enter not into the fields of the fatherless; to carry off the increase of them, to reap their wheat, or mow their grass, or turn in cattle to eat it; or to encroach upon them, take in any part of them, or join the whole to their own; for if there is a woe to them that lay field to field, much more to them that enter into and take the fields of the fatherless, and join them to their own, Isaiah 5:8.

The fatherless are taken under God's special protection. He is their Redeemer, who will take their part; and he is mighty, almighty.

(Compare Proverbs 22:22-23).

The following proverb forms a new whole from component parts of Proverbs 22:28 and Proverbs 22:22.:
10 Remove not ancient landmarks;
And into the fields of orphans enter thou not.
11 For their Saviour is a mighty one;
He will conduct their cause against thee.
בּוא ב separates itself here to the meaning of injuste invadere et occupare; French, empiter sur son voisin, advance not into the ground belonging to thy neighbour (Fleischer). If orphans have also no goel among their kindred (Aquila, Symmachus, Theodotion, ἀγχιστεύς) to redeem by purchase (Leviticus 25:25) their inheritance that has passed over into the possession of another, they have another, and that a mighty Saviour, Redemptor, who will restore to them that which they have lost - viz. God (Jeremiah 50:34) - who will adopt their cause against any one who has unjustly taken from them.

Enter not - To possess their lands.