Khushu' in salah

ٱلَّذِينَ هُمۡ فِى صَلَاتِہِمۡ خَـٰشِعُونَ

"Those who offer their Salât (prayers) with all solemnity and full submissiveness"
(surah mu'minoon: 2

'When they stood for prayer, they faced forward in their prayer, they lowered their gaze to the place of prostration, and they knew that Allaah had turned to them and so they did not look left or right'

 

-As- suyooti, al Durr al-Manthur vol.10 pg.557