PTŠab 10.a:62[2] :ההן ננעה בחדא שרי ובתלת אסור ובתרתיי צריכה‏ : in the case of (using) mint: with one it is allowed, with three it is forbidden, and with two there is doubt
See the entire entry for nānaˁ, nānˁā n.m. mint