With regards to asking the dead or the absent to supplicate to Allah on our behalf, what is the understanding of Ulamah about this issue?
I read that Imam Aaloosi Hanafi Baghdadi does not approve of asking the dead or absent to supplicate for us because they do not have the ability to hear us (Rooh-ul-Ma’ani). I have read though a Hadith of how a Sahabi (Bilal) asked the Prophet Muhammad (Sallallahu Alaihi wa Sallam) at his grave to ask Allah to bless the Muslims with rain and then the Prophet Muhammad (Sallallahu Alaihi wa Sallam) appeared in a dream of the Sahabi and gave the good news of the acceptance of the request. Some Ulamah have declared weak and some have authenticated this Hadith and others like this. Are there Ulamah and Muhaditheen amongst the Ahnaaf too that differ with regards to the authenticity of this incident and others like it? I read a book by Imam Shah Waliullah (Allah have mercy on him) called Al-Balaghul Mubeen and he too in the book states that the Umar Ibn Khattab (Allah be pleased with all the Sahabah) did not ask the dead or the absent to supplicate to Allah. Is it true that there is a difference of opinion about this matter (ask the dead or absent to supplicate on our behalf) as Imam Qaradawi has mentioned (he said that some allow it, some do not and some consider it to be disliked and all have evidence as in any Fiqh issue but what is wrong is to ask someone other than Allah or expect someone other than Allah to have power that belongs to Allah)? Personally, I prefer to stay on the safe side and asked Allah directly but would like some clarification about this issue.

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

The correct opinion of the people of knowledge is that it is not permissible to call upon an absent or dead person, as we are not permitted to seek their help.

In general, it is forbidden to call other than Allah for help, however, it is permissible in particular to seek help of a living person who is in front of you in things that he is able to do.

Allah Says (interpretation of meaning): {…..The man of his (own) party asked him for help against his foe….}[28:15].

However, there is no benefit in calling upon or seeking help of an absent or dead person.  Allah Says (interpretation of meaning): {And who is more astray than one who calls (invokes) besides Allâh, such as will not answer him till the Day of Resurrection, and who are (even) unaware of their calls (invocations) to them? And when mankind are gathered (on the Day of Resurrection), they (false deities) will become enemies for them and will deny their worshipping.}[46:5-6].

Caliph Umar (Radiya Allahu Anhu) and the companions refrained from calling upon the Prophet (Sallallahu Alaihi wa Sallam) (after he passed away) for the prayer for rain and asked Al-Abbas Bin Abdul Mutalib (Radiya Allahu Anhu) the uncle of the Prophet (Sallallahu Alaihi wa Sallam) to make this prayer for rain.  If calling upon the dead person was permissible, the companions would certainly not have refrained from calling upon the Prophet (Sallallahu Alaihi wa Sallam), and called a living person other than the Prophet (Sallallahu Alaihi wa Sallam).  Ibn Abi Shiba and others reported that Malik Al-Darr, who was Umar's treasurer, said: "There was a drought during the reign of Umar and a man came to the Prophet's (Sallallahu Alaihi wa Sallam) grave and said: "O, Prophet (Sallallahu Alaihi wa Sallam) of Allah Say a prayer for rain for your Ummah, they have indeed perished.  So the man saw the Prophet (Sallallahu Alaihi wa Sallam) in a dream, he told him give my Salaam to Umar and tell him that you will have rain."  This Hadith is not correct.

That's why Sheikh Al-Islam Ibn Taymiyah said: 'It is not permissible to call upon or seek the help of the dead amongst Prophets, pious people or others and tell them: 'Call upon your Lord for us.'  No companion or righteous predecessor did this, and no Imam (among the 4 Imams) ordered us to do so, and no Hadith is reported in this regard….'

Therefore, we advise you to refrain from this matter and ask the help of Allah Alone, and there is no harm to ask the pious living people to make a supplication for you.

Allah knows best.