Narrated Ibn 'Abbas:

(regarding) the explanation of "... It throws sparks as Al-Qasr ..." (V. 77:32): We used to collect logs of wood, three cubits long or longer, to store for heating purposes in winter, and we used to call it Al- Qasr, it also means a castle or a fort. "As if they were Jimalatun Sufr (yellow camels or bundles of ropes)" (V.77:33): means the ropes of a ship which are made in bundles till it become as wide as men's waists.

حَدَّثَنَا عَمْرُو بْنُ عَلِيٍّ، حَدَّثَنَا يَحْيَى، أَخْبَرَنَا سُفْيَانُ، حَدَّثَنِي عَبْدُ الرَّحْمَنِ بْنُ عَابِسٍ، سَمِعْتُ ابْنَ عَبَّاسٍ ـ رضى الله عنهما ـ ‏{‏تَرْمِي بِشَرَرٍ‏}‏ كُنَّا نَعْمِدُ إِلَى الْخَشَبَةِ ثَلاَثَةَ أَذْرُعٍ وَفَوْقَ ذَلِكَ، فَنَرْفَعُهُ لِلشِّتَاءِ فَنُسَمِّيهِ الْقَصَرَ‏.‏ ‏{‏كَأَنَّهُ جِمَالاَتٌ صُفْرٌ‏}‏ حِبَالُ السُّفْنِ تُجْمَعُ حَتَّى تَكُونَ كَأَوْسَاطِ الرِّجَالِ‏.‏