Beware - drink not wine - As Samson was designed to be a Nazarite from the womb, it was necessary that, while his mother carried and nursed him, she should live the life of a Nazarite, neither drinking wine nor any inebriating liquor, nor eating any kind of forbidden meat. See the account of the Nazarite and his vow in the notes on Numbers 6:2 (note), etc.

Now therefore beware, I pray thee, and drink not wine nor strong drink,.... Any liquor inebriating and intoxicating, neither new wine nor old wine, as the Targum, and so Jarchi; the reason of this appears in the next verse, because the child she should conceive and bear was to be a Nazarite, and to be one from his mother's womb; and from all such liquors, Nazarites, according to the law, were to abstain, Numbers 6:3.

and eat not any unclean thing; meaning not so much such sort of food as was forbidden by the law to be eaten, which every Israelite was to abstain from, but such as were particularly forbidden to Nazarites, as moist and dried grapes, or anything made of the vine tree, from the kernel to the husk, Numbers 6:3. The reason of this is, because the child in the womb is nourished with the same the mother is; and as this child was to be a Nazarite from the womb, and even in it, his mother was to abstain both from eatables and drinkables forbidden a Nazarite by the law.

Now therefore beware, I pray thee, and drink not wine nor strong drink, and eat not any unclean thing:

13:4 Beware - Because the child was to be a Nazarite from the womb, ver.5, and from the conception; and because the mother's pollution extends to the child, she is enjoined from this time to observe the following rules belonging to the Nazarites. Strong drink - Under which are comprehended the other particulars mentioned, Numb 6:2 -
4. Nor eat - Any of those meats forbidden, Levit 11:1 - 47, which were forbidden to all, but especially to the Nazarites.

13:1-7 Israel did evil: then God delivered them again into the hands of the Philistines. When Israel was in this distress, Samson was born. His parents had been long childless. Many eminent persons were born of such mothers. Mercies long waited for, often prove signal mercies; and by them others may be encouraged to continue their hope in God's mercy. The angel notices her affliction. God often sends comfort to his people very seasonably, when they feel their troubles most. This deliverer of Israel must be devoted to God. Manoah's wife was satisfied that the messenger was of God. She gave her husband a particular account, both of the promise and of the precept. Husbands and wives should tell each other their experiences of communion with God, and their improvements in acquaintance with him, that they may help each other in the way that is holy.