''The Noble Messenger is reported to have said, "On the Day of Qiyaamat, I shall search for the person who used to place his thumbs on his eyes when hearing my name during the Adhaan. I shall lead him into Jannat." [Salat al-Mas'oodi, Vol 2, Chapter 20]

Kissing the nails of the thumbs and the shahadat finger when saying "Muhanunadur-Rasoolullah SallAllaho Alaihi wa Sallam has been classified as weak (zaeef) because it is not proven from a marfoo' Hadith. However, Muhadditheen have agreed that to act upon a zaeef Hadith to incline people towards [good] deeds and instill fear within them is permitted." [Tafseer Rooh al-Bayaan, Vol 3, Page 282]

Imam Hasan Radi ALLAHu Ta'ala Anho states,

من قال حين يسمع المؤذن يقول أشهد أن محمدا رسول الله مرحبا بحبيبي وقرة عيني محمد بن عبد الله ويقبل إبهاميه ويجعلهما على عينيه لم يعم ولم يرمد

''The eyes of he who says 'Marhaban bi-Habibi wa Quratu Aini Muhammad ibn Abdullah' when hearing the Muazzin say "Ash'hadu anna Muhammad ar-Rasoolullah and kisses and places his thumbs on them will never pain nor will he become blind."

[al Maqasid al Hasanah, Hadit 1021, Dar al Kutb Ilmiyah (Berut - Lebenon), Page 385]