Sultan Walad, or to give his full name, Baha al Din Muhammad-i Walad, was the eldest son of Mevlana Jelaluddin Rumi, and like his father, a prolific poet. Regrettably, very ittle of his work is currently available in translation. For more about him, see this earlier post.

Learn the meaning of that secret
That God revealed in the Koran:
Whether He makes you happy or unhappy,
Whether He makes you sad or gives you hope,
Even if you lose all you have
Or suffer extremely in the spirit,
Be patient: a hundred divine graces
Are coming from His hand to you.
He who endures patiently the pain
That is sent from God
Will, it is certain, obtain
The strength and truth of faith.
Marvelous news is sent to the patient; 
They will win a great joy.
You must be able to perceive grace
Even when His divine anger lashes you,
And think of Him always with serenity,
And always, whatever happens, cling to Him
With all you heart and all your soul.