وَمَنْ يَعْمَلْ مِثْقَالَ ذَرَّةٍ شَرًّا يَرَهُ
And whoever does an atom's weight of evil will see it. (Al-Zalzalah 99:8)
The verse prevents one from treating a small wrong as insignificant. After mentioning good, the Qur'an mentions evil, showing that divine reckoning encompasses both kinds of deeds.
Concern for good deeds must therefore be accompanied by care to avoid wrongdoing.