And the evidence for the fact that the Noble Prophet (peace be upon him) forbade performing voluntary prayers after ‘Asr until sunset is that this prohibition applies when the sun is not high and is near to setting.
Sayyiduna Ali (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "No prayer should be offered after Asr except when the sun is white (bright) and high."
Hadith Referenceصحيح ابن خزيمه / جماع أبواب الأوقات التى ينهى عن صلاة التطوع فيهن / 1284