Riyad as-Salihin 120
Abu Dharr (May Allah be pleased with him) reported:
Some people said to Messenger of Allah (ﷺ): "O Messenger of Allah, the rich have taken away (all the) reward. They observe Salat (prayers) as we do; and give Sadaqah (charity) out of their surplus wealth." Upon this he (the Prophet (ﷺ)) said, "Has Allah not prescribed for you (a course) following which you can (also) give Sadaqah? In every declaration of the glorification of Allah (i.e., saying Subhan Allah) there is a Sadaqah, and in every Takbir (i.e., saying Allahu Akbar) is a Sadaqah, and in every celebration of praise (saying Al-hamdu lillah) is a Sadaqah, and in every declaration that He is One (La ilaha illallah) is a Sadaqah, and in enjoining of good is a Sadaqah, and in forbidding evil is a Sadaqah, and in man's sexual intercourse (with his wife) there is a Sadaqah." They (the Companions) said: "O Messenger of Allah, is there reward for him who satisfies his sexual need among us?" He said, "You see, if he were to satisfy it with something forbidden, would it not be a sin on his part? Similarly, if he were to satisfy it legally, he should be rewarded". [Muslim] .
الرابع عنه‏:‏ أن ناساً قالوا‏:‏ يارسول الله، ذهب أهل الدثور بالأجور، يصلون كما نصلي، ويصومون كما نصوم، ويتصدقون بفضول أموالهم قال‏:‏ ‏"‏ أو ليس قد جعل الله لكم ما تصدقون به‏:‏ إن بكل تسبيحة صدقة، وكل تكبيرة صدقة، وكل تحميدة صدقة، وكل تهليلة صدقة، وأمر بالمعروف صدقة، ونهي عن المنكر صدقة وفي بضع أحدكم صدقة قالوا‏:‏ يارسول الله أيأتى أحدنا شهوته، ويكون له فيها أجر‏؟‏‏!‏ قال‏:‏ ‏"‏ أرأيتم لو وضعها في حرام أكان عليه وزر‏؟‏ فكذلك إذا وضعها في الحلال كان له أجر‏"‏ ‏(‏‏(‏رواه مسلم‏)‏‏)‏‏.‏