What does Judges 4:19 mean?

The commander of the defeated Canaanite army, Sisera, is running for his life (Judges 4:15–16). He comes to the tents of a supposed ally in the region: Heber the Kenite (Judges 4:11). Heber has a peace agreement with Sisera's Canaanite king, Jabin of Hazor. Perhaps that's why Sisera so readily agrees to hide in the tent of Heber's wife when she urges him to do so. She has told him not to be afraid and has covered him with a rug to conceal his presence (Judges 4:17–18).

Here, Sisera makes a polite request for water to drink. He is likely exhausted. He has come a long way from the battle. It's not surprising he would be thirsty. At the same time, Sisera's request is a clever means of demanding protection. Ancient middle eastern hospitality included protection for guests—which was implied when the host shared food or drink. According to social customs, offering a guest food was a solemn vow not to harm them.

This makes Jael's response—and what happens shortly after—more surprising. She offers milk, which is heartier than water, and hides Sisera from prying eyes. From the standpoint of that culture, this was practically a sworn oath that she would seek Sisera's good. As it happens, Jael's motives are not helpful. She is certainly offering hospitality in an attempt to deceive, and possibly milk to make Sisera sleepier. By the time her true motives are revealed, it will be too late for the Canaanite general (Judges 4:20–21).