built there an altar] God appointed that in ordinary use there should be but one altar for sacrifice, as there was to be but one tabernacle, and one temple, as types of our onely Saviour Christ, Heb. 13. 10, 11. and therefore the two tribes and half were thought to have sinned, when they built another for this ordinary use, Joshua 22:11. But upon extraordinary and necessary occasions, God allowed his people to build more then this one in number, though they were all one in kinde, both in respect of matter and form, especially when it was done by holy men, and without danger of idolatry: yet with this difference, That the one was to be fixed and permanent, the other to stand onely so long s the necessary occasion continued. And thus we read of divers altars erected; as by Samuel, 1 Sam. 7. 9, 17. 11. 15. and 16. 2, 5. by David, 2 Samuel 24:25. by Elijah, 1 Kin. 18. 32. by Solomon, 1 Kings 8:64.