ٱلَّذِينَ ءَامَنُوا۟ وَعَمِلُوا۟ ٱلصَّٰلِحَٰتِ طُوبَىٰ لَهُمْ وَحُسْنُ مَـَٔابٍ · كَذَٰلِكَ أَرْسَلْنَٰكَ فِىٓ أُمَّةٍ قَدْ خَلَتْ مِن قَبْلِهَآ أُمَمٌ لِّتَتْلُوَا۟ عَلَيْهِمُ ٱلَّذِىٓ أَوْحَيْنَآ إِلَيْكَ وَهُمْ يَكْفُرُونَ بِٱلرَّحْمَٰنِ
"Blessed are those who believe and do righteous deeds; theirs is a good place of return. Thus have We sent you to a community before which many communities have passed away… while they deny al-Raḥmān."
طُوبَىٰ — root ط-ي-ب: to be pleasant, clean, good. The word occurs only here in the Qurʾān, and the lexicographers explain it as "goodness, pleasantness; a good state". In some explanations it is transmitted as the name of a tree in the Garden; I transmit this report, and I do not present it as established knowledge.
That the name al-Raḥmān became a matter of dispute was treated in detail at al-Furqān 25/60 (wa ma'r-Raḥmān) and in Maryam (the sixteen occurrences of the name). I rely on that treatment.
And the word order is worth recording: after stating the messenger's task, the sentence adds the condition of the other side with a circumstantial clause. The reciting goes on, that is, and the denial goes on too — the two at the same time.
قُلْ هُوَ رَبِّى لَآ إِلَٰهَ إِلَّا هُوَ عَلَيْهِ تَوَكَّلْتُ وَإِلَيْهِ مَتَابِ — and the answer is given without entering the dispute, by a statement of position.