To tempt another isn't necessarily a sin.
St. Thomas Aquinas answers "No." to the question "Whether to tempt is proper to the devil?" (Summa Theologica I q. 114 a. 2 co., Freddoso transl. PDF p. 901):
To test or tempt (tentare) is, properly speaking, to make a trial (experimentum) of a thing.
Now a trial is made of a thing in order to find out something about it. And so knowledge (scientia) is the
proximate end of someone who tests.
However, sometimes a further end is sought from this knowledge, and this end may be either good
or bad—good, as when one wants to know how someone stands with respect to knowledge or virtue in
order to help him advance (promoveat), and bad, as when someone wants to find this out in order to
deceive or subvert (subvertat) him.
Given this, we can understand how testing or tempting is attributed to different individuals in
A man is sometimes said to tempt or test someone just in order to find something out, and it is in
this sense that tempting God is said to be a sin. For a man who is uncertain, as it were, presumes to test
God’s power. On the other hand, a man tests or tempts another man sometimes
- in order to help him and
- sometimes in order to harm him.
Now the devil always tests or tempts in order to do harm by urging a man to sin. And it is in this
sense that tempting is called his peculiar role. For even if one man sometimes tempts another man in this
way, he does so insofar as he is a servant of the devil.
By contrast, God is said to test or tempt someone in order to find something out, in that manner of
speaking in which He is said to ‘find out’ what He causes others to know. Hence, Deuteronomy 13:3
says, “The Lord your God tempts (tentat) you, in order that it might be made public whether you love Him.”
Now the flesh and the world are said to tempt instrumentally or materially, viz., insofar as it is
possible to know what sort of man someone is by the fact that he succumbs to or resists the desires of the
flesh or by the fact that he shows disdain for the fortunes and adversities of the world. In addition, the
devil uses the world and the flesh in order to tempt men.
Thus, a man can tempt another man without sin if he does so "in order to help him advance", which is an act of fraternal charity. He sins when tempting another "in order to deceive or subvert him".