wasting the reward of good deeds

وَأَوْفُوا۟ بِعَهْدِ ٱللَّهِ إِذَا عَـٰهَدتُّمْ وَلَا تَنقُضُوا۟ ٱلْأَيْمَـٰنَ بَعْدَ تَوْكِيدِهَا وَقَدْ جَعَلْتُمُ ٱللَّهَ عَلَيْكُمْ كَفِيلًا ۚ إِنَّ ٱللَّهَ يَعْلَمُ مَا تَفْعَلُونَ

Fulfil any pledge you make in God’s name and do not break oaths after you have sworn them, for you have made God your surety: God knows everything you do.

وَلَا تَكُونُوا۟ كَٱلَّتِى نَقَضَتْ غَزْلَهَا مِنۢ بَعْدِ قُوَّةٍ أَنكَـٰثًا تَتَّخِذُونَ أَيْمَـٰنَكُمْ دَخَلًۢا بَيْنَكُمْ أَن تَكُونَ أُمَّةٌ هِىَ أَرْبَىٰ مِنْ أُمَّةٍ ۚ إِنَّمَا يَبْلُوكُمُ ٱللَّهُ بِهِۦ ۚ وَلَيُبَيِّنَنَّ لَكُمْ يَوْمَ ٱلْقِيَـٰمَةِ مَا كُنتُمْ فِيهِ تَخْتَلِفُونَ

Do not use your oaths to deceive each other- like a woman who unravels the thread she has firmly spun- just because one party may be more numerous than another. God tests you with this, and on the Day of the Resurrection He will make clear to you those things you differed about.