यक़ीन था कि

was sure that

→ यक़ीन
phrase Rare #6,296
was sure that यक़ीन था is the past-tense form; यक़ीन है means “am/is sure.”
HI: मुझे यक़ीन था कि वह समय पर आएगी।
EN: I was sure that she would arrive on time.