To believe that anyone can intercede on our behalf or to have our sins forgiven or our wishes fulfilled, implies belief that Allah has some partners. This is idolatry. The Qur’an proclaims that “All intercession belongs to Allah” (39:44), and that there will be “no intercession on the Day of Judgement” (2:254). Examples of verses which corroborate that there will be no intercession on the Day of Judgement are as follows: (2:48), (2:123), (6:51,70,94), (7:53), (21:100), (30:13), (36:23), (40:18), (43:86), (74:48).
It is true that the Quran says that God will not allow intercession from those that people worship other than God. There are two verses, however, which do suggest that God would allow intercession from those that He would allow:
[20.109] On that day shall no intercession avail except of him whom the Beneficent God allows and whose word He is pleased with.
[53.26] And how many an angel is there in the heavens whose intercession does not avail at all EXCEPT after Allah has given permission to whom He pleases and chooses.
The correct view is that it’s not proper to ask saints or angels to intercede on one’s behalf because one cannot know if God has ALLOWED them to interceded or if they would be given permission on the Day of Judgment. Also, it appears that the intercessor has to pray on his/her own and not be asked by the petitioner to act on his/her behalf, as there is nothing in Quran to suggest that God would allow a person to ask somebody else to intercede on his/her behalf.