Manasara 59.37

59.37

nābhyantaṃ meḍhrasīmāntaṃ samaṃ vā yugatrayam
meḍhramūrudīrghaṃ syātpañcaviṃśāṅgulaṃ bhavet

and from the navel down to the limit of the phallus, are equal, or three times four [digits]; / from the phallus, the length of the thigh should be twenty-five digits.