The summons to pay provided for in article L. 221-1 contains, under penalty of nullity:
1° Mention of the writ of execution by virtue of which the proceedings are being carried out with a separate breakdown of the sums claimed in principal, costs and accrued interest as well as an indication of the interest rate;
2° A summons to pay the debt within a period of eight days, failing which the debtor may be forced to do so by the forced sale of his movable property.