He asked water, and she gave him milk
That is, Sisera asked it of her, as the Targum expresses it, when he turned into her tent:
she brought him fresh butter in a lordly dish;
which signifies either the same, the milk with cream on it, for that is meant by butter; or having first taken off the cream, she gave him milk to drink, and then brought the cream in a dish for him to eat, and thereby the more incline him to sleep; and this she brought in a dish fit for any lord or nobleman to eat out of; in such a polite and courteous manner did she use him, so that he could have no suspicion of her having any ill design against him. R. Jonah, as Kimchi notes, interprets this of a dish of the mighty or lordly ones, of the shepherds, the principal of the flock, as they are called in ( Jeremiah 25:34 Jeremiah 25:35 ) , out of which they had used to drink their milk, or eat their cream, and such an one was likely enough to be Jael's tent; from this Hebrew word "sepel", here used, seems to come the Latin word "simpucium" or "simpulum", used in things sacred, and which, according to Pliny F20, was an earthen vessel; and so some of the Rabbins, as Kimchi observes, say, this was a new earthen vial; it is very probable it was a broad platter or dish fit for such an use.
The Brenton translation of the Septuagint is in the public domain.