He is the Truth in His Person and Attributes, He is the most necessary of existences, He is what the whole of existence needs to exist. He has perfect Attributes. He is the one who was, and is, described with magnificence, beauty and perfection. He is the one who was and is known to be beneficent. His saying is the truth, His Actions are the truth, the meeting with Him is the truth, His Messengers are the truth, His Books are the truth, His religion is the truth, worshipping Him alone is the truth, everything that has to do with Him is the truth. This is because Allah is the Truth and what they supplicate to besides Him is false and invalid and because Allah is the Most High, the Great.
“And say: the Truth is from your Lord, so let whosoever who wills believe, and whosoever who wills disbelieve.”
[al-Kahf (18): 29]
“And what is there after truth apart from falsehood?”
[Yunus (10): 32]
“Say: the truth has come and falsehood has departed, indeed falsehood by its nature is bound to depart.”
[al-Isra' (17): 81]
From “Explanation to the Beautiful and Perfect Names of Allah” — Shaykh as-Sa’di (d.1376H)