Expiating by Feeding Non-Muslims
Question

I am in a nonmuslim country and have heard that you must give the food only to Muslims. Is this true and what is the evidence? Must I ask someone whether they are muslim in order for it to be valid or is it ok to just guess?
Praise be to Allah.
Firstly:
Expiation for an oath: Feeding ten poor people or clothing them, and whoever cannot find the means, then fasting for three days; as Allah Almighty says (interpretation of the meaning): Allah will not call you to account for thoughtless oaths, but for the breaking of oaths, the expiation is to feed ten needy people from the average of that which you feed your own families or clothe them or free a slave. But whoever cannot find [the means] - then a fast of three days [is required]. That is the expiation for oaths when you have sworn. And guard your oaths. Thus does Allah make clear to you His verses that you may be grateful. (Al-Ma'idah 5:89).
Secondly:
The feeding is only sufficient if the ten poor people are Muslims, and the same applies to clothing.
It is not sufficient to give any of these to a non-believer, nor is this allowed in the general obligations, such as vows, expiation for fasting, ransom (expiation) for Hajj, nor Zakat, except for the share of those whose hearts are to be reconciled.
Malik (may Allah have mercy on him) said: "It is not sufficient to feed in all expiations except a free Muslim who is poor." End quote from At-Taj Wal-Iklil (5/450).
Ash-Shafi`i (may Allah have mercy on him) said in Al-Umm (7/68): "It is not sufficient to feed in the expiations for oaths except a free Muslim who is in need. If one feeds a non-Muslim who is in need, or a free Muslim who is not in need, or a slave of a man who is in need, that is not sufficient for him, and his ruling is like one who has done nothing and he must repeat it." End quote.
Ibn Qudamah (may Allah have mercy on him) said in Al-Mughni (9/539): "The third condition: that they must be Muslims, and it is not permissible to give it to a non-believer, whether they are under protection (Dhimmi) or at war.
And this was the opinion of Al-Hasan, An-Nakha`i, Al-Awza`i, Malik, Ash-Shafi`i, Ishaq, and Abu `Ubaid." End quote.
Their evidence: The analogy of expiations and vows to the obligatory Zakat, as it is not permissible to give obligatory Zakat to a non-believer, so is the case with expiation.
And the analogy of feeding and clothing in expiation to the freeing of a slave, as faith is a condition in freeing a slave in expiation - despite the differences in opinion on this - so is faith a condition for those to whom expiation is given.
Please see: Ash-Sharh Al-Mumti` (15/167).
Secondly:
It is necessary to verify in the expiation that the recipient is a poor or needy Muslim, and it is not permissible to rely on assumption and estimation, and reaching Muslims is easy through mosques and Islamic centers.
Thirdly:
As for voluntary charity, it is permissible for a non-believer.
Ibn Qudamah (may Allah have mercy on him) said: "And all those who are prohibited from receiving obligatory charity, such as the wealthy, the relatives of the one giving charity, the non-believer, and others, it is permissible to give them voluntary charity, and they are allowed to receive it. Allah Almighty says (interpretation of the meaning): And they give food in spite of love for it to the needy, the orphan, and the captive, and the captive at that time was none but a non-believer.
And Asma' bint Abu Bakr (may Allah be pleased with them both) said: 'My mother came to me while she was a polytheist, so I said: O Messenger of Allah (peace and blessings be upon him) my mother has come to me and she is inclined [towards Islam], should I maintain ties with her? He said: Yes, maintain ties with your mother.'
And `Umar clothed his brother with a garment that the Prophet (peace and blessings be upon him) had given him. Al-Bukhari and Muslim." End quote from "Al-Mughni" (2/276).
And Allah knows best.