His statement, “whose intercession is accepted”: for an intercessor may be granted intercession, or he may not. Thus, he asks Allah to make him an intercessor whose intercession is accepted.
“O Allah, make their scales heavy through him, ...”
His statement, “O Allah, make their scales heavy through him”: that is, the scales of deeds. This is because he is a reward for them; the greater the reward he is for them, the heavier their scales will be through him.
The scales is the plural of scale: that by which people’s deeds will be weighed on the Day of Resurrection.
The scholars differed as to whether it is an actual scale or a figurative expression for the establishment of justice.
The Mu'tazilah held that it is a figurative expression for the establishment of justice, and that there is no physical scale.
The correct view is that it is a physical scale, based on the hadith of the man with the card: “His sins will be placed in one pan, and ‘There is no god but Allah’ in the other pan” (1). This is also the apparent meaning of the Prophet’s ﷺ statement: “Two words, light on the tongue but heavy on the scale” (2). It is therefore a scale with two pans, though we do not know the nature of these two pans, for this belongs to the matters of the unseen of which we have not been informed.
Is it the deed that is weighed, the doer, or the records of deeds?