In one narration the wording is: When the Prophet (peace and blessings be upon him) was asked about the mosque whose foundation was laid on piety (taqwa), the Prophet (peace and blessings be upon him) said: "It means my mosque." Ahmad recorded all of these narrations, and al-Tabarani recorded them in abridged form; the narrators of both are the narrators of the Sahih.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الحج / 5894