Al-Kulayni, as he is usually known, compiled one of the four collections of ahadith (al-kutub al-arb'ah) considered canonical by Twelver Shi'is, Kitab al-Kafi ("Sufficient Book"). The two hadith below come from the one part of the collection, Furu' al-Kafi (approximately, "Sufficient Branches"). Both address the issue of jihad ("struggle"), which has numerous varieties in Sunni and Shi'i jurisprudence, including the now well-known military jihads, offensive and defensive. Honorific formulas repeated after the name of scholars, Infallibles, and the Prophet are omitted.
The translations below are my own.
Kitab al-Jihad (Book of Jihad), Furu' al-Kafi, hadith #8172
"A number of our Companions (narrate) from Ahmad bin Muhammad from 'Ali bin al-Hakam from Aban from Abu 'Abdullah (sixth Imam, Ja'far al-Sadiq), said that the Messenger of God said: 'All goodness is in the sword and being in the sword's shadow and not evaluating the people except (by) the sword, and the swords are keys (in the sense of being "integral") to Paradise and the Conflagration (Hell)."
Kitab al-Jihad (Book of Jihad), Furu' al-Kafi, hadith #8180
" 'Ali bin Ibrahim (narrated) from his father from al-Nawfali from al-Shakuni from Abu 'Abdullah (sixth Imam, Ja'far al-Sadiq), that the Prophet dispatched a raiding part/small military detachment and when they returned he said: "Greetings, people who have spent time/been engaged in the Lesser Jihad ("struggle"; military struggle), the Greater Jihad remained. They said, O' Messenger of God, what Jihad is the greatest? He said: 'Jihad of the self.'"
Struggle of the self" (jihad al-nafs) refers to the struggle against temptation and to better oneself with regard to living a moral and upright lifestyle, according to Islamic principles as expounded in the Qur'an and the Prophet's example. Similarly-worded ahadith also appear in Sunni ahadith collections.