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.
Your answer to that person as well as your prayer in your mosque are the right things to do. Indeed, the differences that exist among Muslims as far as the branches of Fiqh are concerned should not result in causing differences between their hearts or discord amongst them. It is known that Muslims have always prayed, the Maliki behind the Shaafi’i, the Hanafi behind the Hambali and vice versa. The differences in Fiqh matters have never been a cause of dissension or disunity among them.
Ibn Qudama, the great Imam said: “Those who differ (with us) in branches of Fiqh like the followers of Maalik, Abu Haneefah or Ash-Shaafi’i can lead us in prayer. So, the prayer behind them is valid and it is not dislikeable. This is the opinion of Imam Ahmad. The reason for this opinion is that the companions of the Prophet as well as those who followed them in righteousness used to pray behind any of them who happens to be Imam despite their disagreement as regards some Fiqh matters. This then became a consensus among the Ummah.” [End of quote]
As for the way the Hanafi pray Witr, it is one of the correct ways of performing it. As-Sarkhassi said in his book Al-Mabsoot: ‘The book of prayer: Rules of Witr: ‘the number of Witr Rak’ahs and he mentioned some details concerning this issue:
First, Witr is three consecutive Rak’ahs and the person says Salaam after the last one of them. This is our (the Hanafi) opinion. Ash-Shaafi’i said: ‘Witr is only one Rak’ah’. Maalik said: ‘Witr is three Rak’ahs with two Tasleem’. Ash-Shaafi’i gave this Hadeeth as his evidence that the Prophet said: “Allah is Witr (single), so He likes Witr.”
The evidence of the Maaliki School of jurisprudence is the Hadeeth: “Night prayers should be performed in twos (two Rak’ahs followed by two Rak’ahs) and when you fear the dawn, pray one Rak’ah.”
The Hanafi’s opinion is backed by ‘Aa’ishah’s Hadeeth that “The Prophet used to pray three Rak’ahs for Witr.”
To conclude, know that all these scholars have their opinions which are backed by evidence and that your prayer according to the Hanafi School of jurisprudence is correct and valid.
In fact, their view on this issue is also the choice of many other scholars.
For more benefit, please refer to Fataawa 351082, 340912, and 359407.
Allah knows best.