Reference for Pesachim 225:11
(א"ר) שלשה דברים א"ר יהושע בן לוי משום אנשי ירושלים אל תרבה בגנות משום מעשה שהיה בתך בגרה שחרר עבדך ותן לה והוי זהיר באשתך מחתנה הראשון מ"ט רב חסדא אמר משום ערוה רב כהנא אמר משום ממון הא והא איתנהו
requires collecting;<span class="x" onmousemove="('comment',' Do not be certain of the money until you have actually collected it.');"><sup>23</sup></span> in every credit sale it is doubtful whether it [payment] wil be forthcoming or not, and when it is forthcoming it may be bad money.<span class="x" onmousemove="('comment',' If payment is made in small instalments the money may be frittered away.');"><sup>24</sup></span> Three things did R'Johanan say in the name of the men of Jerusalem: when you go out to battle, do not go out among the first but among the last, So that you may return among the first; and treat your Sabbath like a weekday rather than be dependent on your fellow-beings, and strive to be on good terms with him upon whom the hour smiles.