Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates this statement of the Prophet (peace and blessings be upon him): "When the prayer has been established, then come to it calmly, walking with tranquility. Whatever part of the prayer you catch, perform it, and whatever has passed, complete it (afterwards)."
Hadith Referenceصحیح ابن حبان / كتاب الصلاة / 2146
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح: ق - انظر ما قبله.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح على شرطهما.