Fasting on the day of doubt forbidden?

 Kiram reported that he told Imam As-Sadiq (a.): “May my life be sacrificed to you, i decided to fast until the Riser (Qa’im) rises, God is quickening the salvation through him.” He said: “Fast, but do not fast on the journey, nor on the two festivals, nor from the 11th to the 13th day of Dhu-l-Hijjah, nor on the day when there is doubt that it is one of the month of Ramadan.”

Footnote*Sheikh Al Majlisi said:Its possible it was said in Taqqiya.

📚Tahdhib Al Ahkam V4,P302

*The hadith contradicts many authentic ahadith which speak positively of the fast on the day of doubt, its also parallel with the view of our opponents(Omaris) therefore as per  advice from the Imam(as), in case of contradiction we follow that which opposes Omaris.