Sufyaan ath-Thawree 161 AH (May Allah have mercy on him) was asked about the verse “…and man was created weak” (Surah Nisaa: 28) what is man’s weakness?

He replied,

“It is when a woman passes by a man and he does not restrain himself from looking at her nor does he gain any benefit from looking at her, so what is weaker than this?”

سُئِلَ سُفْيَانَ الثَّوْرِيَّ عَنْ قَوْلِهِ تَعَالَى : ( وَ خُلِقَ الْإِنْسَانُ ضَعِيفًا ) مَا ضَعْفُهُ ؟ قَالَ : الْمَرْأَةُ تَمُرُّ بِالرَّجُلِ فَلَا يَمْلِكُ نَفْسَهُ عَنِ النَّظَرِ إِلَيْهَا ، وَ لَا هُوَ يَنْتَفِعُ بِهَا ، فَأَيُّ شَيْءٍ أَضْعَفُ مِنْ هَذَا ؟ .

Source: Hilyatul Awliyaa 7/68