Jami` at-Tirmidhi Book 48, Hadith 174
“Verily, Allah when He created the creation, He wrote with His Hand concerning Himself, that: ‘My mercy prevails over My wrath.’”
“If the believer knew what is with Allah of punishment, none would hope for Paradise, and if the disbeliever knew what is with Allah of mercy, none would despair of (attaining) Paradise.”
The Prophet (ﷺ) entered the Masjid and there was a man who had performed Salat and was supplicating. He was saying in his supplication: “O Allah, none has the right to be worshipped but Allah, You are the One Who gives blessings, Originator of the heavens and the earth, Possessor of glory and generosity (Allāhumma lā ilāha illā ant, al-Mannān, Badī`us-samāwāti wal-arḍ, Dhal-Jalāli wal Ikrām).” So the Prophet (ﷺ) said: “Do you know what he has supplicated Allah with? He has supplicated to Allah by His Greatest Name, the one which if He Is called upon by it, He responds, and when He is asked by it, He gives.”