19:4
قَالَ رَبِّ إِنِّ ى وَهَنَ ٱلْ عَظْمُ مِنِّ ى وَ ٱشْتَعَلَ ٱل رَّأْسُ شَيْبًا وَ لَمْ أَكُنۢ بِ دُعَآئِ كَ رَبِّ شَقِيًّا
He said, "My Lord, indeed my bones have weakened, and my head has filled with white, and never have I been in my supplication to You, my Lord, unhappy.
3:139
وَ لَا تَهِنُ وا۟ وَ لَا تَحْزَنُ وا۟ وَ أَنتُمُ ٱلْ أَعْلَوْنَ إِن كُن تُم مُّؤْمِنِينَ
So do not weaken and do not grieve, and you will be superior if you are [true] believers.
3:146
وَ كَأَيِّن مِّن نَّبِىٍّ قَٰتَلَ مَعَ هُۥ رِبِّيُّونَ كَثِيرٌ فَ مَا وَهَنُ وا۟ لِ مَآ أَصَابَ هُمْ فِى سَبِيلِ ٱللَّهِ وَ مَا ضَعُفُ وا۟ وَ مَا ٱسْتَكَانُ وا۟ وَ ٱللَّهُ يُحِبُّ ٱل صَّٰبِرِينَ
And how many a prophet [fought and] with him fought many religious scholars. But they never lost assurance due to what afflicted them in the cause of Allah, nor did they weaken or submit. And Allah loves the steadfast.
47:35
فَ لَا تَهِنُ وا۟ وَ تَدْعُ وٓا۟ إِلَى ٱل سَّلْمِ وَ أَنتُمُ ٱلْ أَعْلَوْنَ وَ ٱللَّهُ مَعَ كُمْ وَ لَن يَتِرَ كُمْ أَعْمَٰلَ كُمْ
So do not weaken and call for peace while you are superior; and Allah is with you and will never deprive you of [the reward of] your deeds.
4:104
وَ لَا تَهِنُ وا۟ فِى ٱبْتِغَآءِ ٱلْ قَوْمِ إِن تَكُونُ وا۟ تَأْلَمُ ونَ فَ إِنَّ هُمْ يَأْلَمُ ونَ كَ مَا تَأْلَمُ ونَ وَ تَرْجُ ونَ مِنَ ٱللَّهِ مَا لَا يَرْجُ ونَ وَ كَانَ ٱللَّهُ عَلِيمًا حَكِيمًا
And do not weaken in pursuit of the enemy. If you should be suffering - so are they suffering as you are suffering, but you expect from Allah that which they expect not. And Allah is ever Knowing and Wise.