Answer
(Fatwa: 859/859/M=1432)
It is not lawful to supplicate anyone except Allah. It is against the teachings of the holy Quran:
وَلَا تَدْعُ مَعَ اللَّهِ إِلَهاً آخَرَ [القصص : 88]
However, it is right to supplicate with the waseelah (intermediation) of Prophets (عليهم السلام) and Awliya (رحمهم الله). There is a hadith in Bukhari regarding supplication with the waseelah (intermediation) of Hadhrat Abbas (رضى الله عنه).
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband