Is there a hadith which says “One prayer in al-Masjid al-Haram is equivalent to one hundred prayers in the Prophet’s Mosque”?
Question

Is there a hadith says “One prayer in al-Masjid al-Haram is equivalent to one hundred prayers in the Prophet’s Mosque”? This wording is quoted by some of the later scholars.
Praise be to Allah.We have not come across a report with the same wording and in the same order as that which is mentioned in the question, “One prayer in al-Masjid al-Haram is equivalent to one hundred prayers in the Prophet’s Mosque.”
But there is a report with the same meaning and similar wording, as was narrated by Imam Ahmad in al-Musnad (26/41-42) and by Ibn Hibbaan in al-Ihsan (4/499): It was narrated from Hammad ibn Zayd, from Habib al-Mu‘allim, from ‘Ata’ ibn Abi Rabah, from ‘Abdullah ibn az-Zubayr, who said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “One prayer in this mosque of mine is better than a thousand prayers offered in any other mosque except al-Masjid al-Haram, and one prayer in al-Masjid al-Haram is better than a hundred prayers here” – meaning in the mosque of Madinah.
The narrators of this isnad are trustworthy (thiqat).
The commentators on al-Musnad said: The isnad is sahih according to the conditions of Muslim, and its narrators are trustworthy, the narrators of al-Bukhari and Muslim, except for Habib al-Mu‘allim. Al-Bukhari narrated a corroborating report from him and Muslim quoted some of his reports as evidence. End quote.
What appears to be the case is that the wording mentioned in the question points to the same meaning as this hadith of Ibn az-Zubayr.
A number of scholars stated that a report which gives the same meaning, but not the exact wording, may be accepted if the narrator is a scholar and he has the ability to avoid changing the meaning of the report when changing the wording.
Ibn Rajab (may Allah have mercy on him) said:
At-Tirmidhi (may Allah have mercy on him) said:
As for one who mentions the isnad precisely but changes the wording of the report, this is something that is widely practised by the scholars, provided that the meaning is not changed thereby…
What at-Tirmidhi meant by this phrase that we have quoted here is that one who mentions the isnad precisely but changes the text without changing the meaning is still regarded as a trustworthy narrator whose narration carries weight.
He based that on the fact that narrating hadith on the basis of the meaning (not the exact wording) is acceptable, and he narrated that from the scholars. His words may give the impression that there is consensus, but that is not the case; rather it was the view of many of the scholars, and it was stated by Ahmad, who said: The scholars of hadith frequently narrate hadiths by giving the meaning (not the exact wording).
But that is only permissible for one who has knowledge of the language of the Arabs and their styles in expressing meanings, and who knows what phrases could alter the meaning and what phrases do not alter the meaning. This was stated by ash-Shafa‘i."(Sharh ‘Ilal at-Tirmidhi  1/425-427).
And Allah knows best.