All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
This hadeeth is a fabricated lie. Shaykh Al-Albaani mentioned it in Silsilat Al-Ahadeeth Adh-Dha'eefah wa Al-Mawdhoo'ah, no. 215.
Its wording is as follows: "Whoever sends blessings upon me eighty times on Friday, his sins will be forgiven for eighty years." He was asked: "How do we send blessings upon you, O Messenger of Allah?" He said, "Say: 'O Allah, send blessings upon Muhammad, Your slave, Your Prophet, and Your Messenger, the unlettered Prophet’, and count it as one."
Then Shaykh Al-Albaani ruled that it is fabricated and mentioned the reason for that.
Allah knows best.