Hadith 988
Ka'b bin Malik (May Allah be pleased with him) reported:
عن كعب بن مالك رضي الله عنه أن رسول الله صلى الله عليه وسلم كان إذا قدم من سفر بدأ بالمسجد فركع فيه ركعتين . ((متفق عليه)) .
Whenever the Messenger of Allah (ﷺ) returned from a journey, he would proceed straight to the mosque and perform two Rak'ah of (optional) prayer. [Al-Bukhari and Muslim].
In plain words
Whenever the Prophet came back from a journey, he would go first to the mosque and pray two units of prayer before anything else, beginning his return with worship.
Reference : Riyad as-Salihin 988 In-book reference : Book 7, Hadith 33