Many Ahaadith mention huge rewards for virtuous deeds.

Answer

It is not correct to brand such narrations as fabricated. The Ulama who do so appear to be influenced by Salafi attitudes. Salafis summarily label any Hadith which is unpalatable to them as fabricated. A Hadith is not fabricated simply because it is not to be found in the Sihaah Sittah. Besides the Six Authentic kitaabs of Hadith, there are numerous other highly authentic kutub of Ahaadith. Most Ulama are unaware of these Kutub, hence they baselessly criticize and wrongly label many Ahaadith in the way Salafis do.

Imaam Bukhaari

(rahmatullah alayh) alone had memorized over 700,000 Ahaadith while his Saheeh contains only a fraction of these narration. 90% of the Ahaadith are not recorded in the Sihaah Sittah. The Aimmah of Hadith did not claim that Saheeh Ahaadith are restricted to their compilations. On the contrary, they explicitly mentioned that their kitaabs do not encompass all the Saheeh Ahaadith.

It will therefore be in the Imaani interests of molvis who emulate the deviate Salafis to exercise caution and not to recklessly brand Ahaadith as fabrications simply because they are unable to locate the sources. It is indeed dangerous to say that a Hadith is fabricated merely because it is not included in the kutub which are well-known. What is the basis for claiming that the virtues mentioned in the narration pertaining to the Tasbeeh of a menstruating woman are fabricated?

If the Hadith is narrated by senior Ulama and it appears in their kutub, it may not be dismissed as a fabrication simply because it is not to be found in the Sihaah Sittah. When the Hadith does not conflict with any teaching of the Shariah, and on the contrary, it confirms a practice ordered by the Shariah, then what is the imperative need to brand it a fabrication?

The stance for adoption is the instruction of Rasulullah (sallallahu alayhi wasallam) regarding the narrations of Bani Israa-eel. Rasulullah (sallallahu alayhi wasallam) said: "Neither confirm authenticity nor belie it." Since there is the real possibility of the narration being authentic, silence is the best and the safest option. When we are ordered to adopt silence for even the riwaayaat of Bani Israaeel, then to a greater degree will this instruction be applicable when the narration happens to be a Hadith attributed to Rasulullah (sallallahu alayhi wasallam), and when there is no conflict with the Shariah.