Al-Mujadila 58:4

Faman lam yajid fasiyamushahrayni mutatabiAAayni min qabli an yatamassafaman lam yastatiAA fa-itAAamu sitteenamiskeenan thalika litu/minoo billahiwarasoolihi watilka hudoodu Allahi walilkafireenaAAathabun aleem

And he who does not find [a slave] - then a fast for two months consecutively before they touch one another; and he who is unable - then the feeding of sixty poor persons. That is for you to believe [completely] in Allāh and His Messenger; and those are the limits [set by] Allāh. And for the disbelievers is a painful punishment.

But whoever does not find (a slave) has to fast for two consecutive months before the two (spouses) touch one another. Then the one who is not able to do so has to feed sixty indigent persons. This is (laid down) so that you believe in Allah and His Messenger. These are the limits set by Allah; and for the disbelievers there is a painful punishment.