(dated) That which is advantageous to a person; behalf, interest, advantage, profit, benefit.
1676, Joseph Glanvill, Essays on Several Important Subjects in Philosophy and Religion, London: John Baker & Henry Mortlock, Essay 7, “The Summe of My Lord Bacon’s NEW ATLANTIS,” p. 58,
[…] very useful for a Divine, and like to be of more behoof to him, than all the tedious volumes of the Schoolmen […]
1852, William Makepeace Thackeray, Men’s Wives, New York: Appleton, “The Ravenswing,” Chapter 4, p. 119,
Poor Larkins had no one to make epigrams in her behoof; her mother was at home tending the younger ones, her father abroad following the studies of his profession, she had but one protector, as she thought, and that one was Baroski.
They had parents in India—that much Octavian had learned in the neighbourhood; the children, beyond grouping themselves garment-wise into sexes, a girl and two boys, carried their life-story no further on his behoof.