It is narrated from Sayyidah Aishah (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) said to her concerning her Umrah: "Indeed, you will have reward in proportion to your hardship and your spending." This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it! And it has a sahih supporting narration (shahid) as well:

It is narrated from Sayyidah Aishah (may Allah be pleased with her) that the Prophet (peace and blessings be upon him) said to her concerning her Umrah: "The reward of your Umrah is in proportion to your spending."

It is narrated from Sayyiduna Sa'id bin al-Musayyib (may Allah have mercy on him) that Sayyiduna Ali and Sayyiduna Uthman (may Allah be pleased with them both) performed Hajj, and during the journey Sayyiduna Uthman (may Allah be pleased with him) forbade Hajj al-Tamattu' (combining Umrah with Hajj). Sayyiduna Ali (may Allah be pleased with him) was told that he had forbidden tamattu', so Ali (may Allah be pleased with him) said (to his companions): When you see that he has set off, set off too. So Sayyiduna Ali (may Allah be pleased with him) and his companions recited the talbiyah for Umrah, and Uthman (may Allah be pleased with him) did not stop them. Then Ali (may Allah be pleased with him) said: Was I not informed that you forbid tamattu'? He said: Yes. Ali (may Allah be pleased with him) said: Have you not heard that the Messenger of Allah (peace and blessings be upon him) performed tamattu'? He said: Yes indeed. This hadith is sahih (authentic) on the condition of Imam Muslim, but they did not record it.