Verse [ 102:5] كَلَّا لَوْ تَعْلَمُونَ عِلْمَ الْيَقِينِ (No! if you have had sure knowledge..) The word 'if requires a principal clause that seems missing here, but the context suggests that the sense is the following: "If you had the sure knowledge of accountability on the Day of Judgment, you would not have engrossed yourselves in mutual competition in acquiring worldly goods and taking pride in their abundance."