[Sūrah xv. 99]: “Serve the Lord until the certainty come upon thee.”
Muslims say there are three degrees of spiritual knowledge:—
1. ʿIlmu ʾl-Yaqīn (علم اليقين), that which a man apprehends with his intellectual faculties.
2. ʿAinu ʾl-Yaqīn (عين اليقين), that which he sees with the eye.
3. Ḥaqqu ʾl-Yaqīn (حق اليقين), that which he fully embraces with the heart; the highest form of spiritual knowledge, especially of the Unity of God.
YAQT̤ĪN (يقطين). Heb. קִיקָיוֹן. The gourd tree under which Jonah sheltered after he escaped from the belly of the fish. [Sūrah xxxvii. 145, 146]: “We cast him on a barren shore: and he was sick: and we made to grow over him a gourd tree.”
YAʿQŪB (يعقوب). [[JACOB].]
YĀ SĪN (يا سين). The two Arabic letters ى and س corresponding to the English y and s. The title of the XXXVIth Sūrah of the Qurʾān, which begins with these two letters, the mystic import of which is said to be unknown. Al-Baiẓāwī says perhaps they mean Yā Insān! (يا انسان), “O Man!” Ḥusain suggests that they mean Yā Saiyid! (يا سيد), “O Saiyid!” whilst the Jalālān think the meaning is known alone to God. Muḥammad said this chapter was the Qalbu ʾl-Qurʾān, “the heart of the Qurʾān,” and it is consequently held in high estimation. It is usually read to dying persons.
Yā Sīn is a title given to Muḥammad with the belief that he is referred to as “O Saiyid,” in the first verse of the Sūrah referred to.
YAS̤RIB (يثرب). The ancient name of al-Madīnah, mentioned once in the Qurʾān, viz. [Sūrah xxxiii. 13]. According to the traditionist, the Prophet changed the name from Yas̤rib to Madīnatu ʾn-Nabī, “the City of the Prophet,” because Yas̤rib was a name of shame and reproach. (Majmaʿu ʾl-Biḥār, vol. iii. p. 499.)