Midrash for Kiddushin 35:19

"the Hebrew man or the Hebrew woman": Why are (both of) these mentioned? For there obtains with the first what does not obtain with the second, and with the second, what does not obtain with the first. The Hebrew man-servant leaves (his master) with (the lapse of six) years, Yovel, and deduction of money (from the time he has served) — which does not obtain with the Hebrew maid-servant. The Hebrew maid-servant leaves with signs (of puberty), and is not sold and re-sold, and is redeemed perforce — which does not obtain with the Hebrew man-servant. So that since there obtains with the first what does not obtain with the second, and with the second what does not obtain with the first, both must be mentioned.