Makkos, Chapter 1, Mishnah 2. The Mishnah deals with witnesses who testified that a man owed his fellow two hundred zuz, and were then found to be scheming witnesses - since he never owed him those two hundred zuz.
Two penalties fall upon the witnesses:
Lashes - because of "lo saaneh v'reiacha eid shaker" - "do not bear false witness against your fellow," for having transgressed the prohibition of false testimony.
Payment - they must pay two hundred zuz to the man they sought to obligate, by the law of "ka'asher zamam" - "as he schemed to do."
The reason for this, as the Mishnah puts it: the prohibition that brings them to lashes, derived from the verse "do not bear false witness against your fellow," is not the prohibition that brings them to payment. The obligation to pay stems from "as he schemed to do," and so these turn out to be two separate obligations.
The view of Rabbi Meir:
This ruling is the opinion of Rabbi Meir, and he derives it from the law of one who defames his wife: a man who falsely claims about his wife that she was not found to be a virgin receives lashes and also pays. From here Rabbi Meir learned that scheming witnesses too, even though they receive lashes, are still obligated to pay.
The view of the Sages:
The Sages disagree and rule that whoever pays under the law of "as he schemed to do" does not receive lashes for it. In the case before us, where the witnesses pay their fellow the two hundred zuz, the loss they sought to cause him, "as he schemed to do" is actually fulfilled, and therefore they are not given lashes.
However, in the case discussed in the previous Mishnah, where there is no possibility of fulfilling "as he schemed to do" and doing to them what they sought to do to their fellow, the Sages agree that they are given lashes.
In summary: In this Mishnah, Rabbi Meir and the Sages disagree about scheming witnesses who testified concerning a debt of two hundred zuz. According to Rabbi Meir, who derives it from one who defames his wife, they receive lashes and also pay, since the category that brings them to lashes is not the category that brings them to payment. According to the Sages, whoever pays does not receive lashes, and lashes are given only when "as he schemed to do" cannot be carried out against them.