What is the authenticity of the chain of narration for the story of 'Awf ibn Malik's dream vision of his deceased friend Al-Sa'b ibn Jaththamah, mentioned in Ibn al-Qayyim's book "Kitab al-Ruh" (The Book of the Soul), and where can this incident be found, and what are its jurisprudential and theological benefits?

There is no authentic chain of narration for this story. However, there is a similar story mentioned by Al-Zuhri in "Al-Tabaqat Al-Kubra" about Abdullah ibn Salam and Salman Al-Farisi (may Allah be pleased with them both), where they pledged that one would see the other after his death. Abdullah saw Salman in a dream after his passing, and Salman informed him that the best of deeds is reliance on Allah. While the authenticity of these stories cannot be definitively confirmed, a Muslim must believe in the miracles of the awliya' (saints), which is one of the fundamentals of Ahlus-Sunnah wal-Jama'ah.