Assalamoalikum my question is what is the status of this hadith it is reported in a Tradition of the Holy Prophet & that any one who worships Allah for forty days with sincerity of his heart, his heart is made a source of wisdom from ruhul bayan
Answer:
In the name of Allah, the most Beneficent, the most Merciful.
It is reported that the Prophet of Allah said; ‘ If anyone worships Allah for 40 days with sincerity, then Allah causes springs of wisdom to gush from his heart.’ Not only this hadith is found in Ruhul Bayan, but also it can be found in Ma’ariful Qur’an written by Mufti Muhammad Shafi 
. No reference to a hadith book is mentioned.
There are similar hadiths where the significance of 40 days is mentioned. It is a duration, which brings about change in an individual. For example in a hadith of Sahih Bukhari mentions that the fertilized embryo stays in the womb for forty days, after which it becomes a clot of blood. It thereafter transforms into a piece of flesh after forty days. After a further forty days, the sustenance, life span and other factors pertaining to the child are recorded.
In another hadith the Prophet of Allah 
said, “Whoever offers for forty days prayer with congregation, without missing the first Takbir shall be redeemed from the fire as well as from hypocrisy, provided he did so for the sake of Allah.
(Sunan Tirmzi p.33 v.1)
With regards to your question, if a great scholar like Mufti Muhammad Shafi who is well known for his research and knowledge has mentioned it in his tafsir, we will accept it.
Only Allah Knows Best
Mohammed Tosir Miah
Darul Ifta Birmingham.