Sayyiduna Ma'aqal ibn Yassaar (Radhiallaahu Anhu) reports that Rasulullah (Sallallaahu Alayhi Wasallam) said, "Yaseen is the heart of the Qur'aan. nobody who intends the Aakhirat shall recite it except that Allah will forgive him. Recite it upon your deceased." (Sunan Abu Dawud) Imaam Haakim has classified this tradition as Saheeh (authentic); Mustadrak al-Haakim vol.1 pg.565 - see al-Targheeb vol.2 pg.376.
Imaam Ahmad has narrated in his Musnad with his sanad from Safwaan that he said, "The scholars use to say that when it is recited by the deceased, Allah creates ease for him/her." (See Tafseer ibn Kathir vol.3 pg.571)
Sayyiduna Jund ibn Abdullah (Radhiallaahu Anhu) narrates that Rasulullah (Sallallaahu Alayhi Wasallam) said, "Whoever recites Surah Yaseen at night seeking the pleasure of Allah, His sins will be forgiven." (Muwatta Imaam Maalik). Imaam ibn Hibbaan has classified it as Saheeh - Saheeh ibn vol.6 pg.312 (see al-Targheeb vol.2 pg.377)
A similar narration reported by Sayyiduna Abu Hurayra (Radhiallaahu Anhu) has been recorded by Imaam Abu Ya'ala in his Musnad and Hafiz ibn Kathir has classified its chain of narrators as good. (Tafseer ibn Kathir vol.3 pg.570)
Based on this narration, Allamah Munaawi (RA) has analysed that whoever will recite Surah Yaseen during the morning, will also be forgiven, Insha Allah. (See Faydhul Qadeer vol.6 pg.259)
Sayyiduna ibn Abbaas (Radhiallaahu Anhu) says, "Whoever recites Yaseen in the morning, his work for that entire day will be made easy and whoever recites in at the end of the day, his tasks till the next morning will be made easy." (Sunan Daarimi vol.2 pg.549)
A similar narration has also been recorded by Imaam Daarimi from Attaa ibn Abi Rabah.
and Allah Ta'ala Knows Best
Moulana Muhammad ibn Moulana Haroon Abbassommar
FACULTY OF SPECIALTY IN HADITH, www.ask-imam.com