Tafseer of the Letter Alif

Ibn `Abbas is reported as saying: One night, `Ali said to me, “After you accomplish your night prayer, come to me to give you a gift.” It was a night shining with moonlight. `Ali said, “What is the meaning of (the letter) alif in Surah alhamd (No. 1)?” I said, “O `Ali! You know it.” So, he started speaking and spoke for an hour on the alif and another hour on (the letter) lam. He did the same with the other letters and when he finished, the sun was rising. I found that my knowledge as compared to `Ali’s was like a small pond before a sea. (Kashf al-Asrar: 686/10)