Prayer in congregation equals twenty-five prayers, and if one prays it in the open desert completing its bowing and prostration it reaches fifty prayers

Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "Prayer in congregation is equal in merit to twenty-five prayers (compared to praying alone), but if a person prays in an open wilderness (while travelling and the like) and completes its bowing and prostration, its reward reaches fifty prayers."
This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim); they agree on the trustworthiness of Hilal bin Abi Maymunah.

Sayyiduna Abu Hurayrah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "Whoever performs ablution (wudu) well, then goes (to the mosque) and finds that the people have already prayed, Allah, the Mighty and Majestic, will give him a reward like that of those who prayed it and attended it, and nothing will be reduced from their reward."
This hadith is sahih (authentic) on the condition of Imam Muslim, but the two Shaykhs did not record it.