Is there any evidence for the word "al-Azal" (eternity without beginning), and why do we use it if there is no evidence for it? Is it better to use the word "al-Qadim" (the Ancient/Pre-existent) instead?

A distinction must be made between the station of naming (tasmiyah) and the station of informing (ikhbar). The names of Allah are divinely ordained (tawqifiyyah), and it is not permissible to name Allah except with what He has named Himself or what His messengers have named Him. As for the station of informing, the matter is broader. It is permissible to inform about Allah using terms like "al-Azali" (the Everlasting, without beginning) and "al-Qadim" (the Ancient), whereas it is not permissible to name Him with them due to lack of evidence. Al-Azali is that which has no beginning. Al-Qadim can be absolute (like al-Azali) or relative, as in His Almighty saying: "until it returned like the old date stalk."