That the Messenger of Allah ﷺ said: "When one of you (women) has a Mukatab ho has with him what will fulfill (the Kitabah) then observe Hijab from him." (Using translation from Tirmidhī 1261)

"إذا كانَ عنْدَ المُكَاتَبِ ما يُؤدِّي فَاحْتَجِبَنَ مِنْه" .