Abu Huraira (may Allah be pleased with him) reported
Allah's Messenger (peace & blessings of Allah be upon him) as saying:
A strong believer is better
and is more lovable to Allah
than a weak believer,
and there is good in everyone,
(but) cherish that which gives you benefit
(in the Hereafter)
and seek help from Allah
and do not lose heart,
and if anything (in the form of trouble)
comes to you,
don't say:
If I had not done that,
it would not have happened so and so,
but say:
Allah did that
what He had ordained to do
and your " if "
opens the (gate) for the Satan.
{Sahih Muslim}
(Book #033, Hadith #6441)