Al-Awza’i reported: Bilal ibn Sa’d, may Allah have mercy on him, said, “Do not look at the smallness of the sin, but rather look at the One you have disobeyed.”
Source: Ḥilyat al-Awliyā’ 5/223
عَنِ الْأَوْزَاعِيِّ قَالَ قَالَ بِلَال بْن سَعْدٍ رحمه الله لَا تَنْظُرْ إِلَى صُغْرِ الْخَطِيئَةِ وَلَكِنِ انْظُرْ إِلَى مَنْ عَصَيْتَ
5/223 حلية الأولياء لأبي نعيم