From The Saying of The Messenger of Allah (pbuh) (1)

قال رسول الله صلي الله عليه وسلم " سيد الاستغفار" أن تقول : اللهم أنت ربي لا إله إلا أنت ، خلقتني وأنا عبدك ، وأنا على عهدك ووعدك ما استطعت ، أعوذ بك من شر ما صنعت ، أبوء لك بنعمتك علي وأبوء لك بذنبي فاغفر لي ، فإنه لا يغفر الذنوب إلا أنت . قال : ومن قالها من النهار موقنا بها ، فمات من يومه قبل أن يمسي ، فهو من أهل الجنة ، ومن قالها من الليل وهو موقن بها ، فمات قبل أن يصبح ، فهو من أهل الجنة"
الراوي: شداد بن أوس المحدث: البخاري - المصدر: صحيح البخاري - الصفحة أو الرقم: 6306

English translation :
"The best supplication for seeking forgiveness (Syed-ul-Istighfar) is to say : (O Allah! You are my Rubb. There is no true god except You. You have created me, and I am Your slave, and I hold to Your Covenant as far as I can. I seek refuge in You from the evil of what I have done. I acknowledge the favours that You have bestowed upon me, and I confess my sins. Pardon me, for none but You has the power to pardon).' He who supplicates in these terms during the day with firm belief in it and dies on the same day (before the evening), he will be one of the dwellers of Jannah; and if anyone supplicates in these terms during the night with firm belief in it and dies before the morning, he will be one of the dwellers of Jannah " (Al-Bukhari)
Commentary :
1) In this Hadith (saying )the messenger of Allah (peace and blessing of Allah be upon him ) reveals all his submission or resurrender to the will of Allah (pbth ) He Shows all his humbleness to Allah and admitted that he is his slave and his messenger .That shows us the supreme rank of Allah in his pious heart .Let's think deeply in his saying " as far as I can" He proves his humanity and his limited ability and he is always the poor slave to the amnestying of Allah .He (pbuh) confesses that he can not do anything without the support of The Almighty Only God (pbth) and let us also meditate the phrase " my sin " what sin did you commit Oh, my beloved our messenger . Allah (pbth) preserved you and granted you infallibility from any sin but you teach us to impute any good deed to Allah and any evil deeds to the Satan and ourselves and this is the top politeness with Allah (pbth).
2) In this hadith also the messenger teaches us how to enter to Allah the king of all kings ,the lord of all lords and the Only Unique God to that universe .We should stand in front of him pious. humble and submissive with all respect to his Holy Exaltedness and Magnificent then we request what we need .
3) Finally, the messenger of Allah (pbth) tells us that any one supplicates in these terms during the day with firm belief in it and dies on the same day (before the evening), he will be one of the dwellers of Jannah (paradise) and if anyone supplicates in these terms during the night with firm belief in it and dies before the morning, he will be one of the dwellers of Jannah . Thank's our beloved messenger because you invited us to do every good deed and warned us from every evil deeds .