Which colleague is discussed?
Rashi citing Bava Metzi'a 110b: A worker [to whom you owe wages].
Rashi: An Oni.
R. Yonah #1: You were Noder 1 amidst generosity to give a gift to him. Rush to give to him what you promised! A Nediv (generous person) is quick to give.
R. Yonah #2: One who asked to borrow from you.
Gilyonei ha'Shas (Shabbos 21a): The Rishonim called a monetary obligation that one accepted on himself 'Neder', even though it is not a vow.
What is the significance of "Lech va'Shuv"?
R. Yonah: This shows stinginess, therefore he is lazy to give the gift. He sins via telling him to return later - this embarrasses him! It also pains him via an extended hope (13:12).
R. Yonah from Bava Metzi'a 110b: If one has money to pay his worker, and delays paying, the first morning he transgresses "Lo Salin", and after this "Lech va'Shuv."
R. Yonah: This warns that your dealings with people should be pleasant.
Malbim: Even though he does not totally withhold good from its recipient, it is improper to delay doing good until tomorrow, since you can do it today - do not say 'when I am free, I will learn' (Avos 2:4). It is proper to do good in your youth.
What do you have?
Rashi: You have what to give to him.
