1 Corinthians 10:9

Neither let us make trial of the Lord, as some of them made trial, and perished by the serpents.

Make trial of the Lord ... refers to provoking the Lord through disobedience and murmuring against his benign government, in a sense "testing" the Lord to see whether or not he will punish the disobedient. The Old Testament background of this admonition is found in Numbers 21:5,6. Significantly, all sin and disobedience of God fall into the category of making "trial" of him. The particular sins of Israel mentioned here were those of speaking against God and Moses and complaining of the manna.

The Lord ... Many ancient authorities read "Christ" instead of "Lord" (English Revised Version margin); and, as Barnes observed, "It cannot be denied that the more natural construction is ... `Christ' ... rather than `God.'"[18] As the reference is to a time before Christ came, however, the translators rendered it "Lord," thus avoiding the difficulty. The point is not crucial, because, as a matter of fact, they made trial of both God and Christ. The view preferred here is that Paul meant "Christ," the same being another reference to his pre-existence, and indicating that our Lord's pre-incarnation activity included that of shepherding the chosen people in the wilderness. It was not Christ, however, who spake the law to Israel, for Hebrews 1:1 makes it clear that God did that through the prophets, and not through his Son.