He was the son-in-law of Shechaniah - Previously to the coming of Nehemiah, the Jews seemed to be fast intermixing with the heathen, by intermarriages with Ashdodites, Ammonites, and Moabites; see Nehemiah 13:23. Ezra had many evils of this kind to redress, ( Ezra 9:3, etc.), chiefly among the common people, though there were both chiefs and priests in that trespass. But here we find the heathen and Jewish nobles interlinked; and the latter were so far imbued with the spirit of idolatry, that they forgot God, his service, their brethren, and their own souls.
Though Tobiah is called “the servant” or “slave” Nehemiah 2:10, Nehemiah 2:19, and was perhaps a bought slave of Sanballat‘s, yet he was in such a position that Jewish nobles readily contracted affinity with him. This is quite in harmony with the practice of the East, where slaves often fill high positions and make great marriages.