Vaisesika Sūtras
Vaisesika Sūtra 2.2.05
अप्सु शीतता ॥५॥
apsu śītatā ॥5॥
[अप्सु (apsu) - in water;शीतता (śītatā) - coldness;]
Coldness is (the distinguishing mark) of water.