Hadith: Whenever the Messenger of Allah (may Allah's peace and blessings be upon him) mounted his camel while setting out on a journey, he would say Takbīr three times and then say: Glory be to the One who subdued this (ride) for us and we were not ourselves powerful enough to use it as a ride, and to our Lord we shall, indeed, return

عن عبد الله بن عمر رضي الله عنهما أن رسول الله صلى الله عليه وسلم كان إذا استَوَى على بَعِيره خارجًا إلى سَفَر، كَبَّرَ ثلاثا، ثم قال: «سبحان الذي سخَّر لنا هذا وما كُنَّا له مُقْرِنِينَ وإنَّا إلى ربِّنا لـمُنْقَلِبُون، اللهم إنَّا نَسْأَلُك في سفرنا هذا البِرَّ والتَّقْوَى، ومن العمل ما تَرْضَى، اللهم هَوِّنْ علينا سفرنا هذا واطْوِ عنا بُعْدَه، اللهم أنت الصاحب في السفر، والخليفة في الأهل، اللهم إني أعوذ بك مِن وَعْثَاء السفر، وكآبة الـمَنْظر، وسوء الـمُنْقَلَب في المال والأهل والولد». وإذا رجع قالهن. وزاد فيهن «آيبون تائبون عابدون لِربنا حامدون». وفي رواية: كان النبي صلى الله عليه وسلم إذا قَفَل من الحج أو العمرة، كلما أَوْفَى على ثَنِيَّة أو فَدْفَدٍ كَبَّرَ ثلاثا، ثم قال: «لا إله إلا الله وحده لا شريك له، له الملك وله الحمد، وهو على كل شيء قدير، آيِبون، تائبون، عابدون، ساجدون، لربنا حامدون، صدَق الله وَعْدَه، ونصَر عَبْدَه، وهزَم الأحزابَ وحده». وفي لفظ: إذا قَفَل من الجيوش أو السَّرايا أو الحج أو العمرة.
[صحيح] - [الرواية الأولى رواها مسلم، والرواية الثانية متفق عليها، والرواية الثالثة رواها مسلم]

‘Abdullāh ibn ‘Umar (may Allah be pleased with him) reported: Whenever the Messenger of Allah (may Allah's peace and blessings be upon him) mounted his camel while setting out on a journey, he would say Takbīr three times and then say: "Glory be to the One who subdued this (ride) for us and we were not ourselves powerful enough to use it as a ride, and to our Lord we shall, indeed, return. O Allah, we ask You during this journey of ours for righteousness, piety, and such deeds that are pleasing to You. O Allah, make easy for us this journey of ours and make the distance short for us. O Allah, You are the Companion during the journey and the Guardian of the family and the property in our absence. O Allah, I seek refuge in You from the hardships of traveling, unhappiness connected with ghastly scenes, and the evil turns in property and family." On returning, he would recite this supplication, while adding these words: "We are those who return; those who repent; those who worship; and those who praise our Lord." In another narration: “Whenever the Prophet (may Allah's peace and blessings be upon him) returned from Hajj or ‘Umrah and ascended a height or hill, he would say Takbīr three times and say: there is no god but Allah, who has no partner; to Him belongs the sovereignty and due to Him is all praise; and He is omnipotent over all things. We are those who return; those who repent; those who worship; those who prostrate; and those who praise our Lord. Allah has fulfilled His promise, granted His slave victory, and vanquished the confederates alone." In a different wording: “Whenever he returned from battles, Hajj or ‘Umrah.”
[Authentic hadith] - [Narrated by Muslim]

Explanation

Ibn ‘Umar (may Allah be pleased with him) informs us in this Hadīth that whenever the Prophet (may Allah's peace and blessings be upon him) prepared to travel and mounted his ride, he would proclaim the greatness of Allah and say this supplication, which involves a number of sublime meanings, one of which is declaring Allah, the Almighty, far exalted above any need or deficiency. It also expresses a person's appreciation for the favors of Allah. Moreover, the Hadīth asserts one's complete lack of might and power, and his admission that he will return to Allah, the Almighty. Then, it comprises invocation to Allah to bestow His favors and grace and to endow the supplicant with piety and guide him to those deeds that please Him and that He accepts. Also in the Hadīth, the supplicant relies on Allah, the Almighty, and leaves all affairs to Him. Allah, the Almighty, is also implored to preserve the supplicant and his relatives and to ease the hardship of traveling and provide refuge from its evil and harm, like returning and seeing anything unpleasant in his family, property, or children. In the other narration, Ibn ‘Umar (may Allah be pleased with him) relates that whenever the Prophet (may Allah's peace and blessings be upon him) returned from a trip, he would say the above-mentioned supplication and make this addition: We are those who return; those who repent; those who worship; and those who praise our Lord – grateful to Him for our safe return. Whenever the Prophet (may Allah's peace and blessings be upon him) stood on a high place, he would proclaim the greatness of Allah – thus standing humble before His majesty and power – and say: “there is no god but Allah, Who has no partner”, acknowledging the uniqueness and Oneness of Allah in His divinity, lordship, and names and attributes, and that He supports His close servants and allies and makes them victorious.