The Prophet (sallallaahu alayhi wa sallam) once kissed Al-Hasan Ibn ‘Alee (i.e. his grandson) while Al-Aqra’ Ibn Haabis was in his presence. So Al-Aqra’ said to him: "You kiss your children. I swear by Allaah, I have ten children and I never kissed any one of them!" So the Prophet (sallallaahu alayhi wa sallam) said: "He who doesn’t show mercy (to others) will not be shown mercy (by Allaah)."
Verily, mercy - in our religion - encompasses this world and the hereafter, as well as mankind, animals, birds, and the surrounding habitats. Allaah says:
"And My mercy encompasses every thing."
Allaah has described Himself with mercy and He has also described His prophets and righteous servants with it. Allaah says:

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