Is it a condition when calculating the nisab for the zakat on trade goods to take into account the principal capital with which the purchase was made, or is there a significant difference of opinion among scholars on this issue?

If someone possesses commercial goods that reached the nisab (definition) and a year has passed over them, then he sells them for more than their original value; he must pay zakat (definition) on the entire amount over which the year has passed, for the profit is an تابع (ancillary) to the original capital in the obligation of zakat.