From Abu Umamah r.a., Prophet Muhammad (peace and blessings be upon him) said, meaning: "Whoever perform religious obligation during the night of ‘Eid ul Fitr and ‘Eid ul Adha bearing the only hope of obtaining Allah's pleasure, his heart will not die (during the Day of Judgment) unlike the death of hearts (of the Unbelievers) on that Day of Judgment.  (Narrated by Ibn Majah)

Hadith elaboration: On the Day of Judgment, the heart of the Believers will be alive (happy) as they have succeeded in obtaining good rewards and Allah's mercy. However, the heart of those Unbelievers will be dead (disappointed) during that day for they are condemned by Allah and afflicted with the worst return.