بسم الله الرحمن الرحيم
(Fatwa: 1082/1098/L=9/1438)
If you did not say the word of oath verbally then no oath took place. Hence there is no need to pay the kaffarah, however it is haram and major sin to watch porn and masturbate. It is mandatory to do taubah and istighfar.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband
