摩訶止觀 8.22

8.22

兼治者：病兼藥亦兼。如貪欲兼瞋，不淨須帶慈心；病兼一二，藥亦兼一二，是名「兼治」。

As for the combined cure: the illness is combined, so the medicine is also combined. For example, if greed and desire are combined with anger, impurity must be accompanied by loving-kindness; when the illness combines one or two, the medicine also combines one or two; this is called the 'combined cure'.