al-Tabarani recorded that:
The Prophet sallalahu alayhi wassalam said, “The first matter that the slave will be brought to account for on the Day of Judgment is the prayer. If it is sound, then the rest of his deeds will be sound. And if it is bad, then the rest of his deeds will be bad.”
-Al-Albani, Sahih al-Jami, vol.1, p. 503
It was recorded by Malik, Ahmad, Abu Dawud, al-Nasa’I and others:
The Messenger of Allah (peace be upon him) said, “Allah has obligated five prayers. Whoever excellently performs their ablutions, prays them in their proper times, completes their bows, prostrations and khushu`* has a promise from Allah that He will forgive him. And whoever does not do that has no promise from Allah. He may either forgive him or punish him.”
-Al-Albani, Sahih al-Jami, vol. 1, p. 616.
*Khushu` in the prayer is where the person’s heart is attuned to the prayer. This feeling in the heart is then reflected on the body. The person remains still and calm. His gaze is also lowered. Even his voice is affected by this feeling in the heart. For more details on this concept (as well as the difference between it and khudhu`), see Muhammad al-Shaayi, al-Furooq al-Laughawiyyah wa Atharahaa fi Tafseer al-Quran al-Kareem (Riyadh: Maktabah al-Ubaikaan, 1993), pp. 249-254. -islamqa.info
In the holy Qu’ran it is written:
Certainly will the believers have succeeded:
They who are during their prayer humbly submissive,
And they who turn away from ill speech,
And they who are observant of zakah.
-Qur’an 23:1-4
Subhan Allah, when Allah subhanahu wu ta’ala tells us which believers will attain a happy state, the first quality that is enumerated here is humbling oneself in our prayers. This is written in Surat al Mu’minun, the Surat of the true believers.
May Allah, subhanahu wu ta’ala, give us the ability to humble ourselves in our prayers and may he, subhanahu wu ta’ala, make us become true believers. Ameen
In the holy Qu’ran it says (interpretation of the meaning):
Then, there has succeeded them a posterity who have given up As-Salaat (the prayers) [i.e. made their Salaat (prayers) to be lost, either by not offering them or by not offering them perfectly or by not offering them in their proper fixed times] and have followed lusts. So they will be thrown in Hell. Except those who repent and believe (in the Oneness of Allaah and His Messenger Muhammad), and work righteousness. Such will enter Paradise and they will not be wronged in aught.
Surat al Maryam 19:59-60