The narration of Abu Dawud from Shu'bah is more authentic in my view than the narration of An-Nadr. This is how it was reported by more than one narrator from Mansur, from Ribi, from 'Ali. Al-Jarud narrated to us, he said:
'I heard Waki' saying: 'It has been conveyed to me that Rabi' bin Hirash did not utter even one lie in Islam (i.e., after he professed Islam).'"
English reference: Vol. 4, Book 6, Hadith 2145
Arabic reference: Book 32, Hadith 2296