The objective of this study is to examine when and by whom Sunni narrations (isnads) such as "companion > successor..." were incorporated within the Shi'i hadith canons, even though these references are rarely seen in the Shi'i tradition. This study does not merely reveal how the mentioned chains/isnads passed from Ahl al-sunna to the Shi'a but also provides significant ideas with regard to the historical journey of the Shi'i hadith narrative (riwaya). Thus, I hope to obtain clues about the origins of certain narratives that the Shi'a consider critical of Ahl al-sunna but that cannot be proven by Sunni sources. To remain loyal to the limits of this study, I will compare the chapters "Thawab al-a'mal wa-'iqab al-a'mal" within Kitab al-mahasin by al-Barqi, who treats the era of the eleventh imam and al-Ghayba al-sughra (The Lesser Occultation), and Thawab al-a'mal wa-'iqab al-a'mal by al-Sheikh al-Saduq, who conducted his scholarly life during al-Ghayba al-kubra (The Greater Occultation) period, with regard to the use of Sunni chains. These two works are especially important because they reflect tendencies both before and after the Greater Occultation.