It was narrated that Ibn 'Abbas said:
"When 'Umar became Muslim, Jibril came down and said: 'O Muhammed! The people of heaven are rejoicing because of 'Umar's Islam.'" (ID)
English reference (ID): Vol. 1, Book 1, Hadith 103 (ID)
Arabic reference (ID): Book 1, Hadith 108 (ID)