40 days Numerical Value significance chillah Quran Hadith Although it is System Tarteeb only

.........................Although it is ambit clear that this 40 days and 4 month are not a sharaee ruling. It is just tarteeb/system. Otherwise their will be so many problems like Family will not be knowing when the person is returning back.
Only after going in the path of Allah you will taste these difficulties and its Reward.
Still while fixing the days the Ulema of Tabligh movement has tried that there should be some relation from Quran and Hadith. 

Here we are Presenting some Ayats of Quran and Ahadith that establish some numerical Value of 40 days and 4 months.
40-Days from Quran
Allah (ta’ala) mentions in Surah Baqarah verse 51: "We appointed 40-nights for Musa.." (wa Idh wa adna Musa arbaain laylatan ….). This verse establishes the numerical value and importance of 40days. 
40-Days from the Hadith
It will make this nice and easy for the critics. Imaam Tirmidhi (rahmatullahi alayhi) has recorded the following hadith:
"Whoever prays to Allah for forty-days in congregation, reaching the opening Takbeer, will have immunity from two things: freedom from the Fire and freedom from hypocrisy."
(Hasan by Tirmidhi, and also by Nasiruddin al-Albani in Saheeh al-Jaami' (6365).)
('An Anas ibn Maalikin [radhi allahu anhu] qaala, Qaala rasullulahi [sallahu alayhi wa sallam]: man salla lillahi 'arba'aina yauman fee jamaatin yudriku-takbeerata al-ulaa kutibaa lahu baraa-ataani, baraa-atun min-nan naar wa baraa-tun min-nan nifaaqi) - Rawahu Tirmidhi
What we should ask ourselves is, "have we acted according to this hadith knowing well that it brings immunity from Hypocrisy and fire of Hell?"