What is the evidence for the non-obligation of praying in the mosque for a group of travelers?

The questioner:
The second question. May Allah preserve you, O Shaykh. I have learned, O Shaykh, that you say that congregational prayer in the mosque is not obligatory for travelers. Is this correct, O Shaykh? That congregational prayer in the mosque is not obligatory for travelers, if there is a group of travelers who perform the congregational prayer, even in a house,

The Shaykh:
in the village or in the town.

The questioner:
Yes, travelers. Yes, O Shaykh.

The Shaykh:
Does he shorten the prayer?

The questioner:
If they are entitled to shorten the prayer, yes.

The Shaykh:
If he shortens the prayer, he prays with the people for Maghrib and whenever Fajr is, he prays with the people, and he prays Jumu'ah.

The questioner:
But what is the evidence that it is not obligatory for them in the mosque, O Shaykh, the congregation?

The Shaykh:
Is it a prayer or not a prayer, O people?

The questioner:
Today, their prayer.

The Shaykh:
The shortened prayer, O people, does not require them to complete it.

The questioner:
Yes.

The Shaykh:
It does not require them to complete it, and if the Messenger of Allah (peace and blessings be upon him) prays with the congregation, it does not require them to complete it.

The presenter:
Yes, may Allah preserve you. This call was to the Honorable Shaykh 'Abd al-'Aziz ibn Baz on the evening of Friday, the fifteenth or sixteenth of the month of Safar, in the year one thousand...