As is in Shri Sai Satcharita, by Hemadpant .. Chapter XXXVI Page 192

Om Sai Shri Sai Jaya Jaya Sai

At first he was poor, and took a vow to his God, that he would pay his first month's salary, if he got an appointment.  He got one on Rs. 15/- p.m.  Then he steadily got promotions, from Rs. 15/- he got Rs. 30/-, 60, 100, 200 and ultimately Rs. 700/- p.m.  But in his prosperity he forgot clean, the vow he took.  The force of his karma has driven him here, and I asked that amount (Rs. 15/-) from him as Dakshina.

Bow to Shri Sai - Peace be to all