The religion of Islam is complete, and we are lucky to have received divine guidance in all matters. Be it religious in nature, or be it a part of our daily human necessities. In the Quran, Allah tells about how some of Sahabah used to deceive themselves when it came to intercourse with their wives during Ramadan, and Allah (SWT) then revealed the following verse:
“It is made lawful for you to have sexual relations with your wives on the night of As-Sawm (the fasts). They are Libaas [i.e. body-cover, or screen, or Sakan (i.e. you enjoy the pleasure of living with them] for you and you are the same for them. Allaah knows that you used to deceive yourselves, so He turned to you (accepted your repentance) and forgave you. So now have sexual relations with them and seek that which Allaah has ordained for you (offspring), and eat and drink until the white thread (light) of dawn appears to you distinct from the black thread (darkness of night), then complete your Sawm (fast) till the nightfall”
Intercourse during the night in Ramadaan is permitted and is not forbidden, and the time when it is permitted lasts until the onset of dawn. When dawn comes, intercourse becomes forbidden. As proof, this verse clearly states that it is permissible to eat, drink and have intercourse during the nights of Ramadaan until dawn.
After having intercourse it is obligatory to do ghusl as in all other months, before performing fajr prayer. In addition, one can partake in suhoor in the state of janabah and then only perform the ghusl before they have to pray, indicating that one can also partake in sexual activity up to the time of dawn.
During the day of fasting is haraam, and as a result actions that might be leading to arousal should be avoided if one cannot control themselves. This is because intercourse during the day is a sin for which expiation (kafaarah) is required. The kafaarah is to free a slave; if that is not possible then the person must fast for two consecutive months without missing a day; whoever cannot do this must feed sixty poor persons. We see the proof for this from the following hadith, but even then due to the dire state of the sahabi and the great mercy of the Messenger (SAW), we see that he was able to present a compromise for him as our religion does not require hardship upon us.
It was narrated that Abu Hurayrah (may Allaah be pleased with him) said: Whilst we were sitting with the Prophet (peace and blessings of Allaah be upon him), a man came to him and said, “O Messenger of Allaah, I am doomed!” He said, “What happened?” He said, “I had intercourse with my wife when I was fasting [in Ramadaan].” The Messenger of Allaah (peace and blessings of Allaah be upon him) said, “Are you able to free a slave?” He said, “No.” He said, “Are you able to fast for two consecutive months?” He said, “No.” He said, “Can you feed sixty poor persons?” He said, “No.” Then the Prophet (peace and blessings of Allaah be upon him) remained silent for a while, and whilst we were like that, a large vessel of dates was brought to the Prophet (peace and blessings of Allaah be upon him), and he said, “Where is the one who was asking?” He said, “Here I am.” He said, “Take these and give them in charity.” The man said, “Is there anyone more poor than me, O Messenger of Allaah? For there is no household between the two harrahs (lava fields – i.e., in Madeenah) that is poorer than my household.” The Messenger of Allaah (peace and blessings of Allaah be upon him) smiled until his eyeteeth could be seen, then he said, “Feed it to your family.”
(Narrated by al-Bukhaari, 1834, 1835; Muslim, 1111)
So it is incumbent upon every believing man and woman to fast when they have reached maturity, and with that comes the added responsibility of guarding our private regions, even from our spouses contrary to what would be permitted in the other 11 months of the year. This, however, is only for the day, and the night is made for believers to enjoy halaal intimacy, and according to some might even be recommended, just as eating when breaking the fast is because giving it up for a complete day would be analogous to keeping from food or water for the whole day. These would be considered extreme hardships, and are not from the religion. So as the saying goes, Go forth and multiply! but only during the night.