It is narrated from Kathir bin Abbas bin Abdul Muttalib (may Allah be pleased with him) that the Messenger of Allah (peace be upon him) performed two rak'ahs of prayer during a solar eclipse, and in each rak'ah he performed two bowings (ruku).
Hadith Referenceمسند الإمام الشافعي / كتاب الكسوف / 542
Hadith Takhrijاخرجه مسلم الكسوف، باب صلاة الكسوف (902)۔