From the saying of the messenger of Allah (pbuh) (38)

[عثمان أحمد الشيخ]

عن عائشة رضي الله عنها قالت :
" أن نبي الله صلى الله عليه وسلم كان يقوم من الليل حتى تتفطر قدماه ، فقالت عائشة : لم تصنع هذا يا رسول الله ، وقد غفر الله لك ما تقدم من ذنبك وما تأخر ؟ قال : ( أفلا أحب أن أكون عبدا شكورا )" .
الراوي: عائشة المحدث: البخاري - المصدر: صحيح البخاري - الصفحة أو الرقم: 4837
خلاصة حكم المحدث: [صحيح]
Aishah (May Allah be pleased with her) said: The Prophet (PBUH) would stand (in prayer) at night so long that the skin of his feet would crack. I asked him, "Why do you do this while your past and future sins have been forgiven?'' He said, "Should I not be a grateful slave of Allah" (Al-Bukhari and Muslim)

Commentary :
1) The messenger of Allah (pbuh) was always in prayer at night (Tahajid).In Islam the night prayer is very important where A person can be in privacy with Allah ,he can whisper to Him, supplicate to Him, calling Him in the deep darkness of the night while other people in deep sleep.It is a very delicious time where Allah (pbth ) gives his slave gifts that sometimes makes him weeps from happiness and tastes the sweetness of faith
.
2) The messenger of Allah (pbuh) was always prolonged this prayer that the skin of his feet would crack and when our Mother Aishah (May Allah be pleased with her) Why do you do this while your past and future sins have been forgiven?'' He always says "Should I not be a grateful slave of Allah"

3) It is the top of faith.He (pbuh) was the Imam of all believer. The Imam of thankful people .He (pbuh) was our supreme model.He was the most more people in prayer,in fast , in zakat (charity) in loving people,in treating others (Muslims-Christians –Jewish) . I invite all people to read his biography to see that. Oh Allah please collect us with him in the supreme paradise.Ameen .

[هشيم]

Allah bless you