And if someone says: Why is the Creator given the name the One (Al-Wahid) who has no partner in His attributes, just as He is given the name the Unique (Al-Ahad) who has no partner in His essence?

Master al-Sadiq (peace be upon him) informed us that the Name falls upon the Day and does not fall upon the Night, so that we may know with certainty that the names fall upon the Creator—Glory be to Him—in the manifestations which are similar to creatures. As for His Inwardness (Butun), no name, attribute, or description falls upon Him. Just as speech only falls upon the names of the letters specific to their attributes, and sight only falls on their numerical forms. As for its meaning, it is not subject to an attribute, utterance, likeness, description, color, or quality—let alone the Worshiped Meaning (Al-Ma'na al-Ma'bud), which is the meaning of the letters and the meaning of all meanings.

He (mercy be upon him) pointed us toward the increase and decrease of night and day, their occultation and manifestation, so that we may infer from that His existence (the Exalted) represented by them, and to know the nature of imagery, comparison, negation, and affirmation.