All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
Allaah Says (what means): {And when you travel throughout the land, there is no blame upon you for shortening the prayer, [especially] if you fear that those who disbelieve may disrupt [or attack] you. Indeed, the disbelievers are ever to you a clear enemy.}[Quran 4:101]
The above verse does not restrict the shortening of the prayer to the time of fear. Rather, it has a general meaning, which coincided with the state of travel when the verse was revealed; as travelling commonly included danger.
When the companions were no longer in fear, they asked the Prophet about the verse and why they would shorten the prayer after there was no more fear. Thereupon, the Prophet said to them: "...It is a charity which Allaah offered to you, so accept His charity...” This means that Allaah offered them to shorten the prayer even after the fear was over, so shorten the prayer and accept the charity from Allaah, The Most Generous, The Most Merciful.
Hence, there is evidence in the Sunnah that it is permissible to shorten the prayer when in time of security and safety; and Ibn ‘Abbaas said: “We prayed with the Prophet two Rak’as, two Rak’as between Makkah and Madeenah while we were safe and feared nothing between them.”
Allaah Knows best.