Are the narrations "Recite Yaaseen [Quran, chapter 36] on your dead.", and "Chapter Yaaseen is effective on whatever it is intended." Correct?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

Ma'qil Ibn Yasaar narrated that the Prophet said: "Recite Yaaseen [chapter 36] on your dead people." [Ahmad, Abu Daawood, and Ibn Maajah]  There are two unknown narrators in the chain of this Prophetic narration: Abu 'Uthmaan Walees Bin-Nahdi, and his father. Imaam Al-Albaani classified this narration as weak.

As regards the narration "Chapter Yaaseen is effective on whatever it is intended.", we have not come across it in any books of Prophetic narrations after investigation, and no interpreter of this chapter mentioned it when stating the excellence of this chapter.

With regard to reciting this chapter and intending its reward for the dead, this is something which is discussed in Fatwa 84122.

Allaah Knows best.