(3) باب أَيْنَ يَجُوزُ بِنَاءُ الْمَسَاجِدِ
It was narrated that Ibn 'Umar was asked about gardens in which excrement was thrown.:
He said: "If it has been watered several times, then perform prayer there," and he attributed that to the Prophet.
Reference: Sunan Ibn Majah 744
In-book reference: Book 4, Hadith 10
English translation: Vol. 1, Book 4, Hadith 744