أُو۟لَٰٓئِكَ ٱلَّذِينَ نَتَقَبَّلُ عَنْهُمْ أَحْسَنَ مَا عَمِلُوا۟ وَنَتَجَاوَزُ عَن سَيِّـَٔاتِهِمْ
"These are the ones from whom We accept the best of what they did and whose evil deeds We pass over."
I record this as an observation about the word order: the measure is taken not from the average but from the peak. And in answer to it comes the second verb: natajāwazu ʿan sayyiʾātihim — the passing over of the evil deeds.
ت-ج-ا-و-ز — root ج-و-ز: to pass by a place and go on. From Form VI, tajāwuz: to go past without stopping over it. The word conveys not so much erasing as not stopping.
What the two verbs build together is worth recording: one takes the best, the other goes past the worst. That is, the reckoning is set up in the person's favour from both ends.
وَعْدَ ٱلصِّدْقِ ٱلَّذِى كَانُوا۟ يُوعَدُونَ — "the promise of truth that they were promised." The construct waʿdu'ṣ-ṣidq conveys not the content of the promise but its quality: the promise that will be kept.