וַיֹּ֨אמֶר אֵלֶ֤יהָ אֱלִישָׁע֙ מָ֣ה אֶֽעֱשֶׂה־לָּ֔ךְ הַגִּ֣ידִי לִ֔י מַה־יֶּשׁ־לכי [לָ֖ךְ] בַּבָּ֑יִת וַתֹּ֗אמֶר אֵ֣ין לְשִׁפְחָתְךָ֥ כֹל֙ בַּבַּ֔יִת כִּ֖י אִם־אָס֥וּךְ שָֽׁמֶן׃
Kata Elisa kepadanya: “Apa yang dapat kulakukan untukmu? Beritahukanlah kepadaku, apa yang kaumiliki di rumah?” Jawab perempuan itu: “Hambamu ini tidak mempunyai apa pun di rumah, kecuali sebuah buli-buli berisi minyak.”
Kitzur Shulchan Arukh
Do not remove the tablecloth or bread until after Birkas Hamazon. Bread should be on the table at the time of Birkas Hamazon to demonstrate the abundance of goodness from Hashem, blessed be His Name—that He gives us enough to eat and to spare, as Elisha [the prophet] said to his servant:2Kings II Chap. 4: 43. "For so said Hashem, eat and leave over." Another reason for this custom is that Hashem's blessing has no effect on a void. It is only effective on some existing substance, as Elisha said to the wife of Ovadiah:3Kings II 4: 2. "What do you have in the house?" [which I can bless.]
Arukh HaShulchan
And the reason for the thing is because blessing does not reside upon something empty, as it is found with Elisha and [the] Shuanamite. Since he said to her (II Kings 4:2), "[what] you have at home." And in Sanhedrin 92a: Anyone who does not leave bread on his table will not ever see a sign of blessing. And likewise is it in the Zohar, Yitro (87b), and [these are its words: It is forbidden for a person to recite a blessing over an empty table. For supernal blessing does not reside in an empty place. And likewise is it found in the Zohar, Terumah (157b), see there. And our rabbi, the Beit Yosef (Yosef Karo), wrote (Shulchan Arukh, Orach Chayim 180:2), "But he should not bring a whole [loaf of] bread and place on the table. And if he does so, he looks like, 'those who set a table for Luck (Gad),' that the prophet Isaiah mentions (Isaiah 65:11)." But it is only to bring [it] that is forbidden. However if there was a whole bread laying there from before, he does not need to remove it (Taz and Magen Avraham). Hence on Shabbat, when the second Challah of the two breads (lechem mishneh) is laying [on the table], it should not be taken from the table. Yet there will perforce be crumbs left. But if there were no crumbs left on the table, he should bring [them] from another place. And in Job (20:21), It is written, "There is no remnant (sarid) to consume it, hence his fortune will not prosper." So it is from here that our Sages, may their memory be blessed, expounded to leave over bread on the table. As it is implied from this itself that the remnant is crumbs, as that is [the meaning of] the expression, "remnant."