A man given the hadd punishment: is he lashed sitting or lying down?

Ayyub al-Hujaymi reports from his uncle, who said: I saw Salman bin Rabi'ah seize a man in connection with a hadd; he laid him down and then struck him.

Abd al-Rahman says that Sayyiduna Ali (may Allah be pleased with him) struck a man while he was sitting, and upon him was a cloak of the colour of the red of the evening twilight.