The Quran

يا أَيُّهَا الَّذينَ آمَنوا توبوا إِلَى اللَّهِ تَوبَةً نَصوحًا عَسىٰ رَبُّكُم أَن يُكَفِّرَ عَنكُم سَيِّئَاتِكُم وَيُدخِلَكُم جَنّاتٍ تَجري مِن تَحتِهَا الأَنهارُ يَومَ لا يُخزِي اللَّهُ النَّبِيَّ وَالَّذينَ آمَنوا مَعَهُ ۖ نورُهُم يَسعىٰ بَينَ أَيديهِم وَبِأَيمانِهِم يَقولونَ رَبَّنا أَتمِم لَنا نورَنا وَاغفِر لَنا ۖ إِنَّكَ عَلىٰ كُلِّ شَيءٍ قَديرٌ

Muhammad Asad

O you who have attained to faith! Turn unto God in sincere repentance:¹ it may well be that your Sustainer will efface from you your bad deeds, and will admit you into gardens through which running waters flow, on a Day on which God will not shame the Prophet and those who share his faith:² their light will spread rapidly before them, and on their right;³ [and] they will pray: "O our Sustainer! Cause this our light to shine for us forever,⁴ and forgive us our sins: for, verily, Thou hast the power to will anything!"

Sc., "since no human being, however imbued with faith, can ever remain entirely free from faults and temptations".
The implication is that He will not only "not shame" the Prophet and his followers but will, on the contrary, exalt them: an idiomatic turn of phrase similar to sayings like "I shall let you know something that will not be to your detriment" - i.e., "something that will benefit you".
Cf. 57:12 and the corresponding note 12.
Lit., "Complete for us our light", i.e., by making it permanent.