Jamieson, Fausset and Brown on 1 Corinthians 10:9

9. tempt Christ--So the oldest versions, Irenæus (264), and good manuscripts read. Some of the oldest manuscripts read "Lord"; and one manuscript only "God." If "Lord" be read, it will mean Christ. As "Christ" was referred to in one of the five privileges of Israel (1Co 10:4), so it is natural that He should be mentioned here in one of the five corresponding sins of that people. In Nu 21:5 it is "spake against God" (whence probably arose the alteration in the one manuscript, 1Co 10:9, "God," to harmonize it with Nu 21:5). As either "Christ" or "Lord" is the genuine reading, "Christ" must be "God." Compare "Why do ye tempt the Lord?" (Ex 17:2, 7. Compare Ro 14:11, with Is 45:22, 23). Israel's discontented complainings were temptings of Christ especially, the "Angel" of the covenant (Ex 23:20, 21; 32:34; Is 63:9). Though they drank of "that Rock ... Christ" (1Co 10:4), they yet complained for want of water (Ex 17:2, 7). Though also eating the same spiritual meat (Christ, "the true manna," "the bread of life"), they yet murmured, "Our soul loatheth this light bread." In this case, being punished by the fiery serpents, they were saved by the brazen serpent, the emblem of Christ (compare Joh 8:56; He 11:26). The Greek for "tempt" means, tempt or try, so as to wear out the long-suffering of Christ (compare Psa 95:8, 9; Nu 14:22). The Corinthians were in danger of provoking God's long-suffering by walking on the verge of idolatry, through overweening confidence in their knowledge.