Answer:
(Fatwa: 336/336=M/1430)
Yes, it is a big sin; you should avoid it in future. It is also not allowed for entertainment and fun. Repent to Allah and ask for His forgiveness, and marry if you are not yet married.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband
