Sufyan ibn 'Abdullah radiallahu 'anhu said: "O Messenger of Allah, tell me something about Islam, which I cannot ask anyone else besides you." He said: "Say: 'I believe in Allah' and then be steadfast (upon that)." [Sahih Muslim 38]
The hadith is proof that the servant is obligated, after having iman in Allah, to persevere and be steadfast upon obeying Him by performing the obligatory acts and avoiding the prohibited ones. This is achieved by following the Straight Path, which is the firm Religion without drifting away from it, to the right or to the left.
If the Muslim lives through Ramadhan and spent his days in fasting and his nights in prayer and he accustomed himself to doing acts of good, then he must continue to remain upon this obedience to Allah at all times. This is the true state of the slave, for indeed, the Lord of the months is One and He is ever watchful and witnessing over his servants at all times.
Indeed, steadfastness after Ramadhan and the rectification of one's statements and actions are the greatest signs that one has gained benefit from the month of Ramadhan and striven in obedience. They are tokens of reception and signs of success.
Furthermore, the deeds of a servant do not come to an end with the end of a month and the beginning of another, rather they continue and extend until he reaches death. Allah says:
"And worship your Lord until the certainty (death) comes to you." [Al-Qur'an 15:99]
If the fasting of Ramadhan comes to an end, then indeed the voluntary fasting is still prescribed throughout the entire year. If standing in prayer at night during Ramadhan comes to an end, then indeed, the entire year is a time for performing the night prayer. And if the Zakat ul-Fitr comes to an end, then there is still the Zakah that is obligatory as well as the voluntary charity that lasts the whole year. This goes the same for reciting the Qur'an and pondering over its meaning as well as every other righteous deed that is sought, for they can be done at all times. From the many bounties that Allah has bestowed upon his servants is that He has placed for them many different types of righteous acts and provided many means for doing good deeds. Therefore, the ardor and zeal of the Muslim must be constant and he must continue to remain in the service of his Lord.
It is unfortunate to find that some people perform worship by doing different types of righteous deeds during Ramadhan. They guard strictly upon their five daily prayers in the masjid, they recite the Qur'an a lot and they give in charity from their wealth. But when Ramadhan comes to an end, they grow lazy in their worship. Rather, sometimes they even abandon the obligations, both generally, such as praying in congregation, and specifically, such as praying the fajr prayer.
And they commit forbidden acts such as sleeping over the time of prayers, indulging in places of foolishness and entertainment, and mingling in parks, especially on the day of 'Eid. Obtaining help from these evils is only through the grace of Allah. Thus, they demolish what they have constructed and destroy what they have established. This is an indication of deprivation and a sign of perdition. We ask Allah for His safeguarding and protection.
Indeed, this type of people take the example of turning in repentance and ceasing from committing evil deeds as something specific and restricted to the month of Ramadhan. And they stop doing these (good) acts when the month stops. Thus, it is as if they have abandoned sinning for the sake of Ramadhan, and not out of fear of Allah. How terrible is the state of these people, who do not know Allah, except in Ramadhan!
Truly, the success that Allah grants His servant lies in the fasting of Ramadhan. His assisting him to do that is a great favor, thus the calls for the servant to be grateful to his Lord. This understanding can be found in the statement of Allah after completing the favor of the month of fasting:
"(He wants that you) must complete the same number of days, and that you must magnify Allah (by saying Allahu Akbar) for having guided you, so that you may be grateful to Him." [Al-Qur'an 2:185]
The one who is grateful for having fasted, will remain upon that condition and continue to perform righteous deeds. Verily, the true way of the Muslim is that of one who praises and thanks his Lord for giving him the ability to fast and make qiyam. His condition after Ramadhan is better than it was before Ramadhan. He is more receptive to obey, desiring to do good deeds and quick to enforce the obligatory acts. This is because he has gained benefit from this prominent institute of learning. It is that of one who fears for having his fast not accepted, for indeed Allah only accepts from those who fear Him. The righteous predecessors would struggle to complete and perfect their deeds, hoping afterwards, that it would be accepted and fearing that it would be rejected. From the reports of 'Ali, "Be more concerned with having your deeds accepted than the deed itself. Did you not hear Allah say: 'Verily Allah, only accepts those from those who fear Him. (i.e. possess taqwa).' [Al-Qur'an 5:27]" [Lata'if al-Ma'arif, p. 246]
'A'ishah said: "I asked the Messenger of Allah concerning the ayah: 'And the one who are given what they are given and their hearts tremble with fear.' Are they the ones who drink alcohol and steal?" He said: "No, O daughter of as-Siddiq. Rather, they are the ones who fast and pray and give in charity yet fear that it won't be accepted from them. They are the ones who rush to do good deeds and they are the first to do them." [Sahih Sunan at-Tirmidhi 3/79-80]
So be warned and again be warned of turning backward after having attained guidance of going astray after persevering. And ask Allah to provide you with duration in doing righteous deeds and continuity in performing good acts. And ask Allah that He grant you a good end, so that He may accept our Ramadhan from us.
(s) Ahadith as-Siyam - Ahkam wa Adab