From Jabir ibn Abdullah who said: We were with the Messenger of Allah (SAW) on a military raid, and when we returned I made haste on a sluggish camel of mine and a rider caught up with me from behind, prodding my camel with a stick he had, and my camel set off like the finest riding camel you have ever seen. Then I turned around and there I was with the Messenger of Allah (SAW); and He said: What is rushing you, oh Jabir? I said: Oh Messenger of Allah, I have just celebrated marriage vows. And He said: Is it a virgin you married or a previously married woman? I said: Well, a previously married woman. He said: Why not a young maid so you can play with her and she can play with you? And when we got to Medina, we were going to enter, but He said: Wait a little and we will enter at night (that is, evening), so that the disheveled woman can comb herself and the woman whose husband has been absent can trim her pubic hair. And He said: When you get there, plenty of sex, plenty of sex! [al-kais, al-kais].
- Sahih Muslim, The book of suckling

Jabir related that the Messenger of Allah (SAW) said: Whenever you come into town at night, do not go in to see the women of your households until the woman whose husband has been absent has trimmed her pubic hair and the disheveled woman has combed herself. He said: The Messenger of Allah (SAW) said: And you must have plenty of sex, plenty of sex [al-kais, al-kais]. ‘Ubaidallah sought out from Wahab, from Jabir, from the Prophet (SAW), regarding kais. (Hadith in Sahih Al-Bukhari)
Regarding his [Al-Bukhari’s] term “The section of seeking to have children” : in other words, seeking an abundance of sex with the wife, or the objective of exhorting toward the purpose of seeking progeny through sex, not limited merely to pleasure …
His words “Ubaidallah sought out from Wahab, from Jabir, from the Prophet (SAW), regarding kais” … His words “And have plenty of sex” [“fa al-kais”] concerns incitement; this is said to warn against abandoning sex. Al-Khatabi said: Kais here means taking heed, and kais possibly means gentleness and favorable approach. Ibn Al-A’rabi said: Kais is reasoning, as seeking to have children is reasonable; and others said: He meant taking heed against frailty in sex, since He pressed people to have sex. I said: Ibn Hibban in his Sahih collection, after presenting this hadith, was completely certain that kais means sex and its guidance regarding what has been said.