Translation: Aboo Khadeejah Al-Atharee
The standing committee for religious verdicts (of the Kingdom of Saudi Arabia) says:
Commissioning of mosques should be with offering Salaah therein and the continuous remembrance of Allaah with Quraan recitation, chanting of the statements: laa illaha illal laah, subhaanal laah, Al hamdulillaah, teaching of the Islaamic sciences and other activities that may promote it. Allaah - The Exalted - says:
In houses (mosques), which Allâh has ordered to be raised (to be cleaned, and to be honoured), in them His Name is glorified in the mornings and in the afternoons or the evenings. Men whom neither trade nor sale diverts them from the remembrance of Allâh (with heart and tongue), nor from performing AsSalât (Iqâmat-as-Salât), nor from giving the Zakât. They fear a day when hearts and eyes will be overturned (from the horror of the torment of the Day of Resurrection). That Allâh may reward them according to the best of their deeds, and add even more for them out of His Grace. And Allâh provides without measure to whom He wills. (An Noor: 36, 37 and 38)
It was for these purposes that the Messenger of Allaah (salla llaahu alayhi wa aalihee wa sallam) built mosques and the rightly guided Caliphs, the companions (may Allaah bestow his mercy on them) and the Imaams of guidance (may Allaah bestow his mercy on them) after them took to his steps. There is every virtue in adherence to their practice when they open a mosque and as they used to commission it with acts of worship and other symbols of Islaam. There are no authentic reports from him (salla llaahu alayhi wa aalihee wa sallam) nor from the Imaams of guidance after him that they used to commission mosques with celebrations as people do today. If such a practice is to be praiseworthy, the Prophet (salla laahu alayhi wa aalihee wa sallam) would have been the first person to do that, he would have also legislated it for his Ummah and his rightly guided Caliphs and those who came after them would have followed suit. Had these happened, they would have been found in the narrations. For these reasons, the likes of these celebrations are not permissible and one should not honour invitations to them nor should one assist such a cause by making donations of any kind. Goodness is only in the following of the pious predecessors whereas there is every evil in innovation of the later generations. The practice of the Prophet (salla laahu alayhi wa aalihee wa sallam) whereby he would be invited to observe two rakaaat prayer at the place where his host would take as the place of prayer is not an evidence for the celebration of mosque commissioning since he was invited to observe prayer and not for any celebration. He neither traveled for such invitation as such a traveling is prohibited as it falls in the prohibition of traveling for worship in other than the three popular mosques. It thus expected to refrain from such an innovational practice and to remain with the practices in the mosques during the lifetime of the Messenger of Allaah (salla llaahu alayhi wa aalihee wa sallam) and his followers among the Imaams of guidance (may Allaah bestow his mercy on them).
May Allaah exalt the mention of our Prophet Muhammad, his households and his companions and render them safe from every derogatory thing.
(Fataawaa Islaamiyyah (1/ 18) by the standing committee for religious verdicts (Kingdom of Saudi Arabia)).