It is narrated from Aisha (may Allah be pleased with her) regarding the one performing Hajj Tamattu' that if he does not have an animal for sacrifice and has not fasted before 'Arafah, then he should fast during the days of Mina (the days of Tashreeq).
Hadith Referenceمسند الإمام الشافعي / كتاب الحج / 1027
Hadith Takhrijأخرجه البخاري، الصوم، باب صيام ايام التشريق (1999)۔