And Abram said to the king of Sodom, I have lift up mine hand unto the LORD, the most high God, the possessor of heaven and earth, that I will not take from a thread even to a shoelatchet, and that I will not take any thing that is thine, lest thou shouldest say, I have made Abram rich: save only that which the young men have eaten, and the portion of the men which went with me, Aner, Eshcol, and Mamre; let them take their portion.
I suppose I could have thought instead of another gift refusal:
2 Kings 5:15-16 & 26-27
And he returned to the man of God, he and all his company, and came, and stood before him: and he said, Behold, now I know that there is no God in all the earth, but in Israel: now therefore, I pray thee, take a blessing of thy servant. But he said, As the LORD liveth, before whom I stand, I will receive none. And he urged him to take it; but he refused.
And he said unto him, Went not mine heart with thee, when the man turned again from his chariot to meet thee? Is it a time to receive money, and to receive garments, and oliveyards, and vineyards, and sheep, and oxen, and menservants, and maidservants? The leprosy therefore of Naaman shall cleave unto thee, and unto thy seed for ever. And he went out from his presence a leper as white as snow.
Is my brother Abraham or Elisha? Obviously not. His circumstances differ, as do the circumstances of his refusal. That said, I think that only a Biblically illiterate person could think that there cannot be good reasons for refusing gifts.