Thou sittest and speakest against thy brother - To the general character of falsehood and slander there is now added the fact that they were guilty of this in the most aggravated manner conceivable - against their nearest relations, the members of their own families. They were not only guilty of the crime against neighbors - against strangers - against persons to whom they sustained no near relationship; but against those of their own households - those whose characters, on that account, ought to have been especially dear to them. The words ““thou sittest”” probably refer to the fact that they would do this when enjoying social contact with them; in confidential conversation; when words of peace, and not of slander, might be properly expected. The word “brother” “might” be used as denoting any other man, or any one of the same nation; but the phrase which is added, “thine own mother‘s son,” shows that it is here to be taken in the strictest sense.
Thou slanderest - literally, “Thou givest to ruin.” Prof. Alexander renders it, “Thou wilt aim a blow.” The Septuagint, the Vulgate, Luther, and DeWette understand it of slander.
Thine own mother‘s son - It is to be remembered that where polygamy prevailed there would be many children in the same family who had the same father, but not the same mother. The nearest relationship, therefore, was where there was the same mother as well as the same father. To speak of a brother, in the strictest sense, and as implying the nearest relationship, it would be natural to speak of one as having the same mother. The idea here is, that while professing religion, and performing its external rites with the most scrupulous care, they were guilty of the basest crimes, and showed an entire want of moral principle and of natural affection. External worship, however zealously performed, could not be acceptable in such circumstances to a holy God.