al-Kāfi: And from him, from ʿAlī bin Ibrāhīm, from al-Nadhr bin Suwīd, from Hishām bin al-Ḥakam:1

[Hishām bin al-Ḥakam] asked Abā ʿAbd Allāh عليه السلام about the Names of Allāh, and their Derivatives, and from what has ‘Allāh’ been derived from?
He عليه السلام  said: Oh Hishām, ‘Allāh’ has been derived from ‘ilāh’ (god) and the ‘ilāh’ necessitates a ma’lūh2. The Name is not the same as the Named, so whoever who worships the Name without the Meaning has blasphemed, and has [in fact] not worshipped anything! And whoever worships the Name and the Meaning [together], has associated [partners with Allāh], and has [in fact] worshipped two. And whoever has worships the Meaning without the Name – so that is Tawḥīd (Divine Unity). Do you understand, Oh Hishām?
I said: Teach me more (lit. increase me).
He عليه السلام said: For Allāh is ninety nine Names. Had the Name been [the same as] the Named, then every one of them would be a god. On the contrary, ‘Allāh’ is the meanings in which is indicated by these names, and all of these [Names] are other than Him. Oh Hishām, the bread is the name of something that’s eaten, and the water is the name of something that you drink, and the dress is the name of something that is worn, and the fire is a name of something that burns. Do you understand, Oh Hishām? An understanding by which you can defend with, and compete with, against the enemies of Allāh – those that take alongside Allāh others?
I said: Yes
He said: May Allāh benefit you by it and keep you steadfast, Oh Hishām.
Hishām said: By Allāh, no one defeated me in the topic of Tawḥīd, since then until now.

1. al-Majlisi says the ḥadīth has a good (Ḥassan) chain. (Mir’āt al-ʿUqūl, Volume 2, Page 39, Ḥadīth #2)
2. Servant or worshipper.

وعنه : عن علي بن إبراهيم ، عن النضر بن سويد ، عن هشام بن الحكم أنه سأل أبا عبدالله ( عليه السلام ) عن أسماء الله واشتقاقها ، والله مم هو مشتق ؟ فقال : « يا هشام ، الله مشتق من إله ، والإله يقتضي مألوها ، والاسم غير المسمى ، فمن عبد الاسم دون المعنى فقد كفر ولم يعبد شيئا ، ومن عبد الاسم والمعنى فقد أشرك وعبد اثنين ، ومن عبد المعنى دون الاسم فذاك التوحيد ، أفهمت يا هشام ؟ » . قال : قلت زدني . قال : « لله تسعة وتسعون اسماء ، فلو كان الاسم هو المسمى لكان كل اسم منها إلها ، ولكن الله معنى يدل عليه بهذه الأسماء ، وكلها غيره . يا هشام ، الخبز اسم للمأكول ، والماء اسم للمشروب ، والثوب اسم للملبوس ، والنار اسم للمحرق ، أفهمت – يا هشام – فهما تدفع به وتناضل به أعداء الله ، المتخذين مع الله عز وجل غيره ؟ » . قلت : نعم ، فقال : « نفعك الله به وثبتك ، يا هشام » . قال هشام : فو الله ما قهرني أحد في التوحيد حتى قمت مقامي