He replied, “Forty years.”
I said, “And then which?”
He said, “Then, wherever the time for prayer overtakes you, pray, for the whole earth is a mosque.”(1)

According to the People of the Book, it was Jacob ﷺ who founded the Farthest Mosque—the mosque of Aelia, Bayt al-Maqdis, may Allah ennoble it. This view is plausible and is supported by the ḥadīth we have just cited. On that reckoning, Jacob—Israel ﷺ—built it exactly forty years after the Friend of Allah and his son Ishmael erected the Sacred Mosque. Their construction, moreover, took place after Isaac had been born, for when Abraham ﷺ supplicated he said—as Allah, Exalted is He, relates:

“And when Abraham said, ‘My Lord, make this land secure, and keep me and my children away from worshipping idols. My Lord, they have indeed led many people astray. So whoever follows me is truly of me, and whoever disobeys me—You are surely Forgiving, Merciful. Our Lord, I have settled some of my offspring in a valley without cultivation, near Your Sacred House, our Lord, so that they may establish prayer. So incline some hearts among people toward them, and provide them with fruits that they may give thanks. Our Lord, You know what we conceal and what we disclose; nothing is hidden from Allah on earth or in heaven. Praise be to Allah who has granted me, in my old age, Ishmael and Isaac. Truly my Lord is Hearer of supplication. My Lord, make me constant in prayer, and (so too) my offspring. Our Lord, accept my supplication. Our Lord, forgive me, my parents, and the believers on the Day when the Reckoning is set up.’” (Ibrāhīm 35–41)

As for the report(2) that Solomon son of David ﷺ, when he built Bayt al-Maqdis, asked Allah for three favors—as we mentioned under His words, “My Lord, forgive me and grant me a kingdom that shall not belong to anyone after me” (Ṣād 35), and as we shall relate in his story—the intent is that Solomon renovated its structure. We have already noted that the interval between the two constructions was forty years. No one has claimed that only forty years separated Solomon and Abraham except Ibn Ḥibbān in his “Taqāsīm wa-Anwāʿ,” and that view has found no supporters and had no one precede him.

Account of the Building of the Ancient House(3)

Allah, Exalted is He, says:

“And when We settled Abraham in the site of the House and said: ‘Associate nothing with Me, and purify My House for those who circle it, stand in prayer, bow, and prostrate. And proclaim the pilgrimage to humankind: they will come to you on foot and on every lean camel; they will come from every distant ravine.’” (al-Ḥajj 26–27)