A Christian slave: is it paid on his behalf?

Umar bin Abd al-Aziz said: A Muslim man shall pay Sadaqat al-Fitr on behalf of his Christian slave as well.

Al-Awza'i said: It has reached me that Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) used to pay Sadaqat al-Fitr on behalf of his Christian slave as well.

It is narrated from Sulayman bin Musa that Ata was asked about Jewish and Christian slaves: Should Sadaqat al-Fitr be paid on their behalf? He replied: "Yes."

Something similar to the statement of Umar bin Abd al-Aziz is reported from Ibrahim.

Ata said: If you have Christian slaves who are not for trade, then pay Sadaqat al-Fitr on their behalf as well.