John Wesley on Deuteronomy 33:18

Rejoice - Thou shalt prosper and have cause of rejoicing. In thy going out - To war, as this phrase is often used. To sea, in way of traffick, because their portion lay near the sea. And in both respects his course is opposite to that of Issachar, who was a lover of peace and pasturage. He is here joined with Zebulun, both because they were brethren by father and mother too, and because their possessions lay near together. In thy tents - Thou shalt give thyself to the management of laud and cattle, living quietly in thy own possessions.