can one seek the intercession of intercessors such as the Prophet?

The answer to this is as follows: The legitimacy of such a practice was acknowledged unanimously, by all Muslims, until the 8th/ 14th century, after which a number of persons opposed the practice', regarding it as impermissible; this, despite the fact that Qur'anic verses, prophetic sayings, and the established conventional practices of the Muslims all attested to its permissibility. For the intercession of the intercessors is, in essence, a prayer on behalf of others, and there is no doubt that asking for the prayers of the pious -and especially the Prophet-is both permissible and laudable.

A hadith of the Prophet, related by lbn 'Abbas, makes it clear that the intercession of a believer consists in the making of a petition on behalf of others:

It Is thus clear that the intercession of forty believers in the funeral prayer of a dead person is nothing other than a prayer for him to be forgiven by God.
A glance at the pages of history reveals that the companions of the Prophet asked him in their own lifetimes for his intercession. Tirmidhi relates from Anas b. Malik:

The reality of seeking intercession, then, is nothing other than the request for prayers from the intercessor. Examples of this practice can be found in the period of the Prophets; as related in the Qur'an:
1. The sons of jacob, after the disclosure of their wicked acts, asked their father to implore God's forgiveness of them. Jacob accepted their petition and promised to do so at the appointed time.

2. The Qur'an says:

3. Likewise it says, regarding the hypocrites:

It is evident that being averse to asking the Prophet to seek forgiveness for one-that is, asking for his intercession-is a sign of hypocrisy and pride; conversely, making this request is a mark of faith and humility before God.

Our aim in this discussion has been to affirm the validity and legitimacy of seeking intercession. Now, the fact that the intercessor, in the verses quoted, is no longer alive does not detract from the argument propounded. Even if it be supposed that these verses pertain to the living and not the dead, this still does not diminish the validity of the principle. For, if seeking intercession from the living is not shirk (polytheism) then, naturally, seeking intercession from the dead will not be so either; the question of whether the intercessor is alive or dead is immaterial as regards the distinction between Tawhid and shirk; The only question is whether, when these blessed souls receive requests for intercession, they can hear them; this is a question that relates to the reality and the benefit of the connection between the two groups, the petitioners and those petitioned, and it will be addressed below, in the debate on tawassul.
Here it should be noted that seeking the intercession of the Prophets and the saints by true, monotheistic believers differs fundamentally from the requests by the polytheistic idolators for the intercession of their idols. For the monotheists make their request for intercession from the saints while acknowledging two principles:
1. The station of intercession is the preserve of God, and is determined according to His disposition, as it is said:

2. The intercessors to whom the monotheist believer extends his hands, seeking their prayers, are purified slaves of God, blessed by their proximity to Him, and thus those whose prayers are accepted.
Taking due note of these two principles, the difference between the monotheists seeking intercession and the polytheistic idolators alive at the time of the Prophet becomes readily apparent. Firstly, the polytheists believed in setting no kind of limits or conditionality on 'the making of their requests for intercession. The monotheists, on the other hand, following the guidance of the Holy Qur'an, know that the station of intercession is the exclusive preserve of God, and the success of the intercession of other intercessors is totally contingent upon His permission and good pleasure.
Secondly, the polytheists alive at the time of the Prophet believed that their idols, though fashioned by their own hands, were gods and lords, imagining in their deluded folly that these lifeless objects had been endowed with a share in divinity and lordship. The monotheists, on the contrary, consider the Prophets and the Imams as slaves of God, and continuously chant phrases such as 'His slave and His Prophet' and 'The righteous slaves of God'. The vast distance that separates these two divergent attitudes towards intercession could hardly be clearer.

Therefore, the attempt to prove the illegitimacy of the principle of intercession in Islam by reference to verses that invalidate the seeking of intercession by the idolators from their idols, is nothing but an utterly misplaced analogy, a piece of baseless sophistry.