He who is free from all error, absentmindedness, is free from incapability and from any kind of defect.
YA-QUDDUS
The hearts of those who repeats this name 100 times each day will be free from anxiety.
Allah is the One Who is completely clean and pure. He doesn't have any flaws, weaknesses or dirtiness. He cleans the earth with rain and wind, and teaches us to be clean, giving us soap to wash away dirt, wudu to remove sins, and the Quran to purify our hearts.
Pure means that Allah doesn't have any flaws or weaknesses,for example He never loses His temper or gets sleepy. Clean means He doesn't have any dirtiness, for example He never uses bad words or gets sweaty or stinky like we do. People have flaws, weaknesses and become dirty in many ways, but Allah is free from all of these things because He is Al-Quddoos, The Clean & Pure!