قُلْ هُوَ اللَّهُ أَحَدٌ ۝ اللَّهُ الصَّمَدُ ۝ لَمْ يَلِدْ وَلَمْ يُولَدْ ۝ وَلَمْ يَكُن لَّهُ كُفُوًا أَحَدٌ

The subject of the chapter is monotheism, or the oneness of God. The concept of God has been presented here in its purest form, ridding it of all polluting associations which people of every age have brought to it. There is no plurality of gods. There is only one God. All are dependent upon Him, but He is not dependent on anybody. He Himself has power over everything. He is far above being the progeny of anybody or having any offspring. He is such a unique Being that there is nobody like Him or equal to Him in any manner whatsoever. This is an early Makkan chapter. The doctrine of God’s pure unity, or the Divine oneness, is clearly stated here: God is not many, He is only one. Everyone is in need of Him, but He is not in need of anyone. He reigns over all things of the heavens and the earth. Unlike human beings, He has no son or father. He is eternal, without beginning or end, and is thus a Unique Being who has no equal. This chapter has been called the essence of the Quran. The Prophet Muhammad once described this chapter as ‘equivalent to one-third of the whole of the Quran.’ (Bukhari, Muslim)

— Source: Tazkirul Quran (Maulana Wahiduddin Khan) via Quran.com (112:1)