وَالَّذِينَ امَنُواْ وَعَمِلُواْ الصَّالِحَاتِ
...
And those who believe and do righteous good deeds,
meaning, their hearts were truthful and their limbs obedient with the righteous acts they were commanded, all the while abandoning the evil they were prohibited from doing.
...
سَنُدْخِلُهُمْ جَنَّاتٍ تَجْرِي مِن تَحْتِهَا الاَنْهَارُ
...
We shall admit them to Gardens under which rivers flow (Paradise).
meaning, they will think of where they want these rivers to flow and they will flow there,
...
خَالِدِينَ فِيهَا أَبَدًا
...
to dwell therein forever,
without end or being removed from it.
...
وَعْدَ اللّهِ حَقًّا
...
Allah's promise is the truth,
meaning, this is a true promise from Allah, and verily, Allah's promise shall come to pass.
Allah then said,
...
وَمَنْ أَصْدَقُ مِنَ اللّهِ قِيلً
and whose words can be truer than those of Allah!
meaning, none is more truthful in statement and narration than Allah.
There is no deity worthy of worship, or Lord except Him.
The Messenger of Allah used to proclaim in his speech,
إِنَّ أَصْدَقَ الْحَدِيثِ كَلَمُ اللهِ وَخَيْرَ الْهَدْيِ هَدْيُ مُحَمَّدٍصلى الله عليه وسلّم
وَشَرَّ الاُْمُورِ مُحْدَثَاتُهَا وَكُلَّ مُحْدَثَةٍ بِدْعَةٌ وَكُلَّ بِدْعَةٍ ضَلَلَةٌ وَكُلَّ ضَلَلَةٍ فِي النَّار
The most truthful speech is Allah's Speech, and the best guidance is the guidance of Muhammad.
The worst matters are the newly invented (in religion), every newly invented matter is an innovation, and every innovation is a heresy, and every heresy is in the Fire.