It is from the Sunnah to pray wearing sandals.

The Shaykh : The Prophet (peace and blessings be upon him) said: Because the Jews do not pray in their sandals, it is therefore from the Sunnah to pray in one's sandals, just as many people pray in their leather socks; there is no difference between the leather sock and the sandal. However, the sandal is considered blameworthy because it is a Sunnah that has been neglected. This is if the mosques are carpeted as they are today. In the past, mosques were covered with stones, pebbles, small stones, or sand, and no harm would come from wearing sandals. But now that they are covered with carpets, if people entered wearing their sandals, they would visibly and clearly defile the mosque, because most people do not care if their sandals have dirt or filth on them. For this reason, scholars have now held that a person should not enter the mosque wearing his sandals, considering that it is carpeted with coverings that would become soiled if a person entered in his sandals. If a person wishes to practice the Sunnah, let him pray in his house wearing his sandals, whether for the Tahajjud prayer, the regular voluntary prayers, or the like. In doing so, he fulfills the command of the Prophet (peace and blessings be upon him) in his saying:
Then, regarding the hadiths: the hadith of Abu Hurayrah and the hadith of Jabir that the Prophet (peace and blessings be upon him) said... The hadith of Abu Hurayrah is two: meaning either one wears both sandals or one removes both. As for wearing one and leaving the other, this is what has been prohibited.
The reason for this, and Allah knows best, is that this Islamic religion came with justice, even in clothing. One does not put a sandal on one foot and leave the other, because this is injustice to the other foot that is not shod. Therefore, the Prophet (peace and blessings be upon him) prohibited walking in one sandal. The scholars said that even if it is to fix the other one, one should stand until the other is equal to it, then put it on.
For this reason, it came in the second hadith of Abu Hurayrah:
As for the hadith of Jabir (may Allah be pleased with him) that Abu Dawud narrated: This is regarding a sandal that requires effort to put on the foot. Because if a person puts on a sandal while standing and the sandal requires effort, it might fall off when he lifts his foot to adjust the sandal. It might fall on the back of his head, exposing his private parts, or cause him harm. As for the sandals we know now, there is no harm in a person putting them on while standing, and this does not fall under the prohibition, because the sandals we have are easy to remove and put on. And success is from Allah.