The Shank Will Be Entwined With The Shank- Quran 75:29
According to Ghamidi Sahab, the idom used in 68:42 is ’ یَوْمَ یُکْشَفُ عَنْ سَاقٍ ‘ , which as an idiom refers to agony derived from literal situation of agony where even decent women raise their ankle coverings to run. However, 75:29 is referring to powerlessness and weakness that one won’t be able to do anything about this situation, the wordings are different here وَالْتَفَّتِ السَّاقُ بِالسَّاقِ , its not the same idiom from what I have gathered.