The Shaykh (Al-Mufid), may Allah سبحانه وتعالى support him, said: ‘And the traveler, if he fears that sleep will overcome him due to the exhaustion he has experienced and he will not be able to rise at the end of the night, then let him perform the prayer of his night (‘salat al-layl’) at its beginning, after the Isha prayer…’, up to his statement: ‘And whoever is too weak to perform the night prayer standing…’