The nations have their false gods made by their own hands, but the Lord is not like these gods; he is the portion of Jacob.
A portion
refers to something that belongs to someone. Jacob
is just another way to refer to the nation of Israel. So, the Lord is the portion of Jacob
because he is the one who formed all things
and he set Israel aside as the tribe of his inheritance.
The background here could very well be the words the Lord spoke to Israel at Mt Sinai through Moses, Thus shall you say to the house of Jacob, and tell the people of Israel: You yourselves have seen what I did to the Egyptians, and how I bore you on eagles' wings and brought you to myself. Now therefore, if you will indeed obey my voice and keep my covenant, you shall be my treasured possession among all peoples, for all the earth is mine: and you shall be to me a kingdom of priests, a holy nation. These are the words that you shall speak to the people of Israel
(Exodus 19:3–6). Israel and the Lord are bound together in a deep and intimate covenant relationship in which the Lord would show steadfast love and protection towards his people whom he has set apart as his own, and they would love and obey him wholeheartedly because he is their God. The one who has done all this is the Lord of hosts,
the all-powerful creator of everything. In such a covenant relationship Israel had no need to fear the false gods of the nations, and they certainly had no right to offer their worship to any other god other than the Lord.1
16 Not like these is he who is the portion of Jacob, for he is the one who formed all things, and Israel is the tribe of his inheritance; the LORD of hosts is his name.