In what way he was connected by marriage we are not told, but inasmuch as both Tobiah and his son had married Jewish wives, one or both of these may have been closely related to the high priest, chap.
vi.

17, 18.

So the friendship with the Samaritans had grown; Eliashib had probably visited Samaria, and had been made much of and royally entertained by Sanballat and his secretary; and in proportion as his friendship with the heathen had grown warm, his love and earnestness in the Lord's service had grown cold.
In the latter part of the Book of Nehemiah we never find Eliashib coming forward as a helper in any good work.

Ezra stands in the huge pulpit to read the law of God, thirteen of the chief men in Jerusalem stand by him to help him, but Eliashib the high priest, who surely should have been well to the front in that pulpit, is conspicuous by his absence.
How could he stand up and read the law to the people, when he knew, and they knew, that he was not keeping it himself?
Nehemiah draws up a covenant between the people and their God, in which they promise to obey God and keep His commandments.

No less than eighty-four seals are fastened to that document, but not one of those seals bears the name of Eliashib.
How could he engage to keep that covenant, one article of which was a promise to have nothing to do with the heathen, when at the very time he was living on the most friendly terms with both Sanballat and Tobiah?
Then comes the grand service of dedication, when the city and all it contained was devoted to God.