Yahya related to me from Malik, from Ibn Shihab, from Said ibn al-Musayyab, that Umar ibn Abi Salama once asked Umar ibn alKhattab for permission to do umra in Shawwal. He gave him permission, so he did umra and then went back to his family, and he did not do hajj.
أَنْ يَعْتَمِرَ فِي شَوَّالٍ فَأَذِنَ لَهُ فَاعْتَمَرَ ثُمَّ قَفَلَ إِلَى أَهْلِهِ وَلَمْ يَحُجَّ