Umar ibn Muhammad
أبو حفص عمر بن محمد بن الحسن
Fourth generation, died 250 AH in Kufa. Named in the chains of 3 narrations of the library, 2 in Bukhari, 1 in Nasa'i.
3narrations name him
2collections
250 AHhe died, in Kufa
In the books of narrators: Truthful, صدوق ربما وهم.