I am an ailing woman but I intend to perform Hajj; what you command me (to do)? He (the Holy Prophet) said: Enter into the state of Ihram (uttering these words) of condition: I would be free from it when Thou wouldst detain me. 'He (the narrator) said: But she was able to complete (the Hajj without breaking down).
Sahih Muslim Book 15, Hadith 114