Praying for Kaafir

With regard to praying for kaafirs, this falls into two categories:
1 – Praying for a kaafir to be guided to Islam and so on. This is permissible. It was narrated from Ibn ‘Umar (may Allaah be pleased with him) that the Messenger of Allaah (peace and blessings of Allaah be upon him) said: “O Allaah, support Islam with the man who is more beloved to You: Abu Jahl or ‘Umar ibn al-Khattaab.” Narrated by al-Tirmidhi, 3681; classed as saheeh by al-Albaani. Here he was praying for one of them to be guided.
2 – Praying for him to be forgiven and so on. This is forbidden according to scholarly consensus.
Al-Nawawi said: With regard to offering the funeral prayer for a kaafir and praying for forgiveness for him, this is haraam according to the text of the Qur’aan and scholarly consensus.
Al-Majmoo’ 5/120
It says in Tuhfat al-Muhtaaj: It is haraam to pray for a kaafir and for one whose Islam is in doubt with regard to matters of the Hereafter, even if that is one of his parents. (3/141).
With regard to praying for him to be healed from sickness, this is permissible if it serves a purpose, such as if one hopes that he will become Muslim and that his heart will be softened and so on. This is indicated by the hadeeth of the Sahaabi who recited ruqyah for the chief of a tribe who had been stung by a scorpion. This has been discussed in the question no. 6714. Praying for healing comes under the same heading as ruqyah.
Indeed it is permissible for you to visit him during this sickness, because when a person is sick his heart is softer and is more likely to accept the truth. The Prophet (peace and blessings of Allaah be upon him) had a Jewish boy who used to serve him, and he fell sick. The Prophet (peace and blessings of Allaah be upon him) came to visit him; he sat by his head and said to him: “Become Muslim.” He looked at his father, who was present, and he (the father) said to him: “Obey Abu’l-Qaasim (peace and blessings of Allaah be upon him).” So he became Muslim and the Prophet (peace and blessings of Allaah be upon him) went out saying, “Praise be to Allaah Who has saved him from the Fire.” Narrated by al-Bukhaari, 1356.
Ibn Hajar said: This hadeeth indicates that it is permissible to employ a mushrik as a servant and to visit him if he falls sick, and this is a form of kind treatment.
But praying for a kaafir to be healed does not mean that one has befriended him or loves him or prefers him to a believer, as explained above. And Allaah knows best.
EXTRACTED FROM http://islamqa.info/en/47322