Chapter on Guarantee
Man Lā Yaḥḍuruh al-Faqīh|Volume 3|Book 1|Chapter 38
وَ - سَأَلَ دَاوُدُ بْنُ سِرْحَانَ أَبَا عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ: عَنِ اَلْكَفِيلِ وَ اَلرَّهْنِ فِي بَيْعِ اَلنَّسِيئَةِ قَالَ "لاَ بَأْسَ".
Dawud ibn Sirhan asked Abu Abdullah عليه السلام: About a guarantor (kafil) and a pledge (rahn) in a deferred sale (bay' al-nasi'ah). Imam عليه السلام said: "There is no harm in it."
- Ṣaḥīḥ al-Faqīh, p. 194