What is the meaning of Allaah’s name al-Mateen (the Most Strong) ?
Praise be to Allaah. Allaah is the Owner of Power, the Most Strong, i.e., He has immense Power. He is All-Strong and All-Powerful; His Power never fails, and whatever He does, it never results in difficulty, discomfort or tiredness for Him. His Power is perfect and complete, it never wanes or decreases – exalted be Allaah far above such a thing.
Sharh Asmaa’ Allaah ta’aala al-Husnaa by Dr. Hissah al-Sagheer, p. 229