Hadith 6-26

حَدَّثَنا عَلِىُّ بْنُ الفَضْلِ البَغدْاديُّ قالَ: سَمِعْتُ أَبَا عُمَرَ صاحِبَ أَبي العَبَّاسِ ثَعلَبٍ يُسْأَلُ عَنْ مَعْنى‏ قَوْلَهُ‏ صَلَّى اللهُ عَلَيْهِ وَآلِهِ:«إنِّي تارِكٌ فِيكُمُ الثَّقَلَيْنِ» لَمْ سُمِّيا بِالثَّقَلَيْنِ؟ قالَ: لأَنَّ الَّتمَسُّكَ بِهِما ثَقِيلٌ.

Ali ibn Al-Fadhl al-Baghdadi narrated that he had heard that Abu Umar - the friend of Abil Abbas Tha’lab was asked the following question regarding the meaning ‘I will leave two heavy things with you’ that the Prophet (S) said. He was asked, ‘Why are these two things called heavy things?’ He replied, ‘Since they are very hard to adhere to.’