Albert Barnes Commentary Deuteronomy 22:6-8

"If a bird`s nest chance to be before thee in the way, in any tree or on the ground, with young ones or eggs, and the dam sitting upon the young, or upon the eggs, thou shalt not take the dam with the young: thou shalt surely let the dam go, but the young thou mayest take unto thyself; that it may be well with thee, and that thou mayest prolong thy days. When thou buildest a new house, then thou shalt make a battlement for thy roof, that thou bring not blood upon thy house, if any man fall from thence." — Deuteronomy 22:6-8 (ASV)

These precepts are designed to cultivate a spirit of humanity. Compare Deuteronomy 25:4; Leviticus 22:28; and 1 Corinthians 9:9–10.

Deuteronomy 22:8. The roofs of houses in Palestine were flat and used for various purposes. Compare Joshua 2:6; 2 Samuel 11:2; Acts 10:9. A battlement was almost a necessary protection. It was to be, according to the rabbis, at least two cubits high (about 3 feet).