Intercession

وَلا يَمْلِكُ الَّذِينَ يَدْعُونَ مِنْ دُونِهِ الشَّفَاعَةَ إِلَّا مَنْ شَهِدَ بِالْحَقِّ وَهُمْ يَعْلَمُونَ
43:86
And those whom they invoke instead of Him have no power of intercession – except for those who bear witness to the truth knowingly [e.g. Jesus (AS) and the angels who know where the objects of intercession lie].
Exegesis:
Intercession is acceptable but only those who bear witness to the truth may intercede for others. The blessed Verse is about the false belief held by polytheists imagining that idols or others such as angels and Jesus (AS) could intercede on their behalf and save them from torment. The Verse is saying that no one may intercede except those who bore witness to the truth knowingly. The Verse indicates that verbal testimony is insufficient in matters of faith but it must be borne out of knowledge and certitude. It may also allude that interceders solely intercede on behalf of believers in Divine Unity.

http://www.maaref-foundation.com/english/library/quran/light/light_16/043/86.htm