It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that the Holy Prophet (peace and blessings of Allah be upon him) said: Two men will not be gathered together in Hell in such a way that one of them harms the other. The companions (may Allah be pleased with them) asked, "O Messenger of Allah, who are those people?" He said: The Muslim who kills a disbeliever and then adopts the straight path.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 9186