As for the evidence of this actually happening – in addition...

Among the verse of the Holy Qur’an that mention it are: مَنْ ذَا الَّذِي يَشْفَعُ عِنْدَهُ إِلَّا بِإِذْنِهِ “Who is he that can intercede with Him but by His permission?” (Qur’an, Surah Baqarah 2:255) لَا يَمْلِكُونَ الشَّفَاعَةَ إِلَّا مَنِ اتَّخَذَ عِنْدَ الرَّحْمَٰنِ عَهْدًا “They shall not control intercession, save he who has made a covenant with the Beneficent God.” (Qur’an, Surah Maryam 19:87) يَوْمَئِذٍ لَا تَنْفَعُ الشَّفَاعَةُ إِلَّا مَنْ أَذِنَ لَهُ الرَّحْمَٰنُ وَرَضِيَ لَهُ قَوْلًا “On that day shall no intercession avail except of him whom the Beneficent God allows and whose word He is pleased with.” (Qur’an, Surah Taha 20:109) وَلَا يَشْفَعُونَ إِلَّا لِمَنِ ارْتَضَىٰ “And they do not intercede except for him whom He approves.” (Qur’an, Surah Anbiya 21:28) وَلَا تَنْفَعُ الشَّفَاعَةُ عِنْدَهُ إِلَّا لِمَنْ أَذِنَ لَهُ “And intercession will not avail aught with Him save of him whom He permits.” (Qur’an, Surah Saba 34:23) And traditions: They are to the limit of Tawatur (widely related) but we shall mention only a few that are quoted in the third volume of Biharul Anwar :[^2] It is narrated from the Holy Prophet (S) that he said: “For every prophet there is a prayer that he seeks from the divine court, I have concealed my prayer for the intercession of my Ummah on the Judgment Day.” It is narrated from His Eminence that he said: “Three groups would come forward to intercede on the Judgment Day and they would be allowed to intercede: prophets, then scholars and then martyrs.”[^3] It is narrated from His Eminence that he said: “One who has not believed in my pool, the Almighty Allah would not make him come at my pool and one who does not have faith in my intercession, the Almighty Allah would not allow him to receive my intercession.