There are about 1,500 scribal errors in the Hebrew Scriptures. The letters ו (vav) and י (yod), for instance, were often confused by ancient copyists of the Bible. The two letters are so similar that they are easily confused. In fact, writing by mistake a vav instead of a yod, or vice versa, is the most common scribal error in the Bible.
The only difference between the Hebrew personal pronouns for “he” and “she” is the middle letter yod or vav. Confusion of vav and yod often resulted in a copying mistake, the writing of הוא (hu, he) instead of היא (hi, she), and vice versa. If, for instance, an earlier scribe happened to make the letter י (yod) of היא (hi, she) a little too long, then the scribe who next copied that text might mistakenly read the היא as הוא (hu, he) (e.g., 1 Kgs. 17:15; Job 31:11; Isa. 30:33). Or, conversely, if a scribe made the ו (vav) of הוא a little too short, then the next copyist might read the הוא as היא (e.g., 1 Kgs. 17:15; 1 Chron. 29:16; Job 31:11; Ps. 73:16; Eccl. 5:8).