for them are Gardens of Delight. To abide therein.
means, there they will enjoy all kinds of delights and pleasures, food, drink, clothing, dwelling-places, means of transportation, women, a light of beauty and delightful sounds, which have never crossed the mind of any human being. They will stay there forever, never leaving and never desiring change.
وَعْدَ اللَّهِ حَقًّا
It is a promise of Allah in truth.
meaning, this will undoubtedly come to pass, for it is a promise from Allah, and Allah never breaks His promise, because He is the Most Generous Bestower Who does what He wills and is able to do all things.
And He is the All-Mighty,
Who has subjugated all things and to Whom all things submit,
in what He says and what He does, Who has made this Qur'an a guidance to the believers.
قُلْ هُوَ لِلَّذِينَ ءَامَنُواْ هُدًى وَشِفَأءٌ وَالَّذِينَ لَا يُوْمِنُونَ فِى ءَاذَانِهِمْ وَقْرٌ وَهُوَ عَلَيْهِمْ عَمًى
Say;"It is for those who believe, a guide and a healing. And as for those who disbelieve, there is heaviness (deafness) in their ears, and it is blindness for them. (41;44)
وَنُنَزِّلُ مِنَ الْقُرْءَانِ مَا هُوَ شِفَأءٌ وَرَحْمَةٌ لِّلْمُوْمِنِينَ وَلَا يَزِيدُ الظَّـلِمِينَ إَلاَّ خَسَارًا
And We send down of the Qur'an that which is a healing and a mercy to those who believe, and it increases the wrongdoers nothing but loss. (17;82