Allah does not accept the Salaah of one who allows his pants over his ankles

Rasulullah said: "Certainly Allah does not accept the Salaah of one who allows his pants over his ankles" (Sunan Abi Dawud #638)

The Word "Solah" in the Quran - Al-Maeda

(1) O ye who believe! when ye prepare for prayer, wash your faces, and your hands (and arms) to the elbows; Rub your heads (with water); and (wash) your feet to the ankles. If ye are in a state of ceremonial impurity, bathe your whole body. But if ye are ill, or on a journey, or one of you cometh from offices of nature, or ye have been in contact with women, and ye find no water, then take for yourselves clean sand or earth, and rub therewith your faces and hands, Allah doth not wish to place you in a difficulty, but to make you clean, and to complete his favour to you, that ye may be grateful.
( سورة المائدة , Al-Maeda, Chapter #5, Verse #6)

(2) Allah did aforetime take a covenant from the Children of Israel, and we appointed twelve captains among them. And Allah said: "I am with you: if ye (but) establish regular prayers, practise regular charity, believe in my apostles, honour and assist them, and loan to Allah a beautiful loan, verily I will wipe out from you your evils, and admit you to gardens with rivers flowing beneath; but if any of you, after this, resisteth faith, he hath truly wandered from the path or rectitude."
( سورة المائدة , Al-Maeda, Chapter #5, Verse #12)

(3) Your (real) friends are (no less than) Allah, His Messenger, and the (fellowship of) believers,- those who establish regular prayers and regular charity, and they bow down humbly (in worship).
( سورة المائدة , Al-Maeda, Chapter #5, Verse #55)

(4) When ye proclaim your call to prayer they take it (but) as mockery and sport; that is because they are a people without understanding.
( سورة المائدة , Al-Maeda, Chapter #5, Verse #58)

The Word "Solah" in the Quran - An-Nisaa

(1) O ye who believe! Approach not prayers with a mind befogged, until ye can understand all that ye say,- nor in a state of ceremonial impurity (Except when travelling on the road), until after washing your whole body. If ye are ill, or on a journey, or one of you cometh from offices of nature, or ye have been in contact with women, and ye find no water, then take for yourselves clean sand or earth, and rub therewith your faces and hands. For Allah doth blot out sins and forgive again and again.
( سورة النساء , An-Nisa, Chapter #4, Verse #43)

(2) Hast thou not turned Thy vision to those who were told to hold back their hands (from fight) but establish regular prayers and spend in regular charity? When (at length) the order for fighting was issued to them, behold! a section of them feared men as - or even more than - they should have feared Allah. They said: "Our Lord! Why hast Thou ordered us to fight? Wouldst Thou not Grant us respite to our (natural) term, near (enough)?" Say: "Short is the enjoyment of this world: the Hereafter is the best for those who do right: Never will ye be dealt with unjustly in the very least!
( سورة النساء , An-Nisa, Chapter #4, Verse #77)

(3) When thou (O Messenger. art with them, and standest to lead them in prayer, Let one party of them stand up (in prayer) with thee, Taking their arms with them: When they finish their prostrations, let them Take their position in the rear. And let the other party come up which hath not yet prayed - and let them pray with thee, Taking all precaution, and bearing arms: the Unbelievers wish, if ye were negligent of your arms and your baggage, to assault you in a single rush. But there is no blame on you if ye put away your arms because of the inconvenience of rain or because ye are ill; but take (every) precaution for yourselves. For the Unbelievers Allah hath prepared a humiliating punishment.
( سورة النساء , An-Nisa, Chapter #4, Verse #102)

(4) When ye pass (Congregational) prayers, celebrate Allah.s praises, standing, sitting down, or lying down on your sides; but when ye are free from danger, set up Regular prayers: For such prayers are enjoined on believers at stated times.
( سورة النساء , An-Nisa, Chapter #4, Verse #103)

(5) The Hypocrites - they think they are over-reaching Allah, but He will over- reach them: When they stand up to prayer, they stand without earnestness, to be seen of men, but little do they hold Allah in remembrance;
( سورة النساء , An-Nisa, Chapter #4, Verse #142)

The word "Solah" In the Quran - Baqara

(1) Who believe in the Unseen, are steadfast in prayer, and spend out of what We have provided for them;
( سورة البقرة , Al-Baqara, Chapter #2, Verse #3)

(2) And be steadfast in prayer; practise regular charity; and bow down your heads with those who bow down (in worship).
( سورة البقرة , Al-Baqara, Chapter #2, Verse #43)

(3) Nay, seek (Allah's) help with patient perseverance and prayer: It is indeed hard, except to those who bring a lowly spirit,-
( سورة البقرة , Al-Baqara, Chapter #2, Verse #45)

(4) And remember We took a covenant from the Children of Israel (to this effect): Worship none but Allah. treat with kindness your parents and kindred, and orphans and those in need; speak fair to the people; be steadfast in prayer; and practise regular charity. Then did ye turn back, except a few among you, and ye backslide (even now).
( سورة البقرة , Al-Baqara, Chapter #2, Verse #83)

(5) And be steadfast in prayer and regular in charity: And whatever good ye send forth for your souls before you, ye shall find it with Allah. for Allah sees Well all that ye do.
( سورة البقرة , Al-Baqara, Chapter #2, Verse #110)

(6) O ye who believe! seek help with patient perseverance and prayer; for Allah is with those who patiently persevere.
( سورة البقرة , Al-Baqara, Chapter #2, Verse #153)

(7) Guard strictly your (habit of) prayers, especially the Middle prayer; and stand before Allah in a devout (frame of mind).
( سورة البقرة , Al-Baqara, Chapter #2, Verse #238)