Sayyiduna Ali (may Allah be pleased with him) narrates from the Noble Prophet (peace and blessings be upon him) that he (peace be upon him) said: "Do not perform prayer after Asr, except if you are praying while the sun is still high."
Hadith Referenceصحيح ابن خزيمه / جماع أبواب الأوقات التى ينهى عن صلاة التطوع فيهن / 1285