عن عبد الله بن مسعود رضي الله عنه أن رسول الله صلى الله عليه وسلم قال: "مَنْ مات وهو يدعُو مِنْ دون الله نِدًّا دخَل النَّار". [صحيح] - [رواه البخاري] المزيــد ...
‘Abdullāh ibn Mas‘ūd (may Allah be pleased with him) reported: “The Messenger of Allah (may Allah's peace and blessings be upon him) said: "Whoever dies while invoking anything other than Allah as a rival will enter Hell." Sahih/Authentic. - [Al-Bukhari]
In this Hadīth, the Prophet (may Allah's peace and blessings be upon him) tells us that if someone devotes something to other than Allah, when it should be devoted to Him alone, and he dies persisting in doing so, his final consequence will be the Hellfire.
Whoever dies as a polytheist will enter Hellfire; he will dwell therein eternally if his polytheism is a major one. If his polytheism is minor, on the other hand, he will receive punishment there for as long as Allah wills and then get out of it.
The deeds that matter are the final ones.
Supplication is an act of worship that should be devoted to none but Allah Almighty.