Translation:He offered his house for the festival.
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I think if there is a recipient you use "para". "The apple is for her" = "La manzana es para ella", Ella is a recipient of the apple. I guess "the festival" was the recipient of the "house". https://www.youtube.com/watch?v=_cBJoq479NM That video explains 4 uses of "para" and if a sentence does not fit one of the 4 rules you can usually can get by with "por".
POR - Motion/Direction - Duration of action - Means of action - Support for - Go in search of - Because of / account of / behalf of - In exchange for - Unit measure (kilometros por hora) - Passive (by)
PARA - Destination/direction - Deadline/time (by/for) - To achieve a goal - Recipient (para senor X) - Comparison - Working "para" someone - Opinion