حَدَّثَنَا سُلَيْمَانُ بْنُ حَرْبٍ، حَدَّثَنَا حَمَّادُ بْنُ زَيْدٍ، عَنْ ثَابِتٍ، عَنْ أَنَسٍ، قَالَ كُنَّا عِنْدَ عُمَرَ فَقَالَ نُهِينَا عَنِ التَّكَلُّفِ.
Narrated Anas: We were with 'Umar and he said, "We have been forbidden to undertake a difficult task beyond our
capability (i. e. to exceed the religious limits e. g., to clean the inside of the eyes while doing ablution).
Sahih al-Bukhari 7293