Hadith.1289 - In the book of Al-Hakam ibn Miskin, it is reported that Imam Jafar ibn Muhammad Al-Sadiq (as) was asked about a man who arrives from his journey during the time for a prayer.
Imam (as) said
"If he does not fear that the time for the prayer will expire, he should complete it (in full). But if he fears that the time will expire, he should shorten it”.