Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyiduna Uthman bin Abu al-As Thaqafi (may Allah be pleased with him) that the Noble Prophet (peace and blessings of Allah be upon him) said: "At midnight, the heavens are opened and a caller announces: Is there anyone who calls so that his supplication may be accepted? Is there anyone who asks so that he may be given? And is there anyone afflicted so that his affliction may be removed? There is no Muslim who supplicates and Allah Almighty does not accept his supplication, except a woman who earns through her private parts (i.e., a prostitute) and a tax collector (the supplications of these two are not accepted)."