Sayyiduna Anas bin Malik (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) said: "When you come to the prayer, come in a state of calm. Pray whatever of it you catch, and make up afterwards whatever has already passed."
Tabarani recorded it in al-Mu'jam al-Awsat, and its narrators have been declared trustworthy. It is also narrated through another chain whose narrators are the narrators of the Sahih, except that its wording is: Hammad says: To my knowledge he narrated it as a marfu' hadith up to the Prophet (peace and blessings be upon him).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 2090
Hadith Gradingمحدثین:إسنادہ صحیح، اس کے تمام راوی ثقہ ہیں اور اصل حدیث صحیحین
Hadith Takhrij«المعجم الأوسط للطبراني باب العين من اسمه عبد الله 4505»