It is narrated from Sayyiduna Ibn Amr, may Allah be pleased with him, that a man came to the Prophet Muhammad, peace and blessings be upon him, and said, "O Messenger of Allah! Allow me to free myself from manly attributes and to crush my glands." The Prophet Muhammad, peace and blessings be upon him, said: "The crushing (castration) of my Ummah is fasting and standing (in prayer)."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 6612
Hadith Gradingحکم دارالسلام:صحيح لغيره دون ذكر القيام، وهذا إسناد ضعيف لضعف ابن لهيعة و حيي بن عبد الله