Before Jacob came to Haran, the Holy One, blessed be He, sent a plague upon Laban's flock, and only a few remained. We learn this from here, as it is said, "And Jacob fed the rest of Laban's flock," meaning what remained from the plague, so that the flock might be made fruitful and multiply on account of Jacob's arrival. From this you may say: there is a foot that lays a house waste, and there is a foot that brings blessing to a house, as it is said, "and the LORD has blessed you on account of my foot [my coming]" (Genesis 30:30).
There Is a Foot That Blesses a House and a Foot That Ruins It
Yalkut Shimoni on Torah 130:8
קוֹדֶם עַד שֶׁלֹּא בָּא יַעֲקֹב לְחָרָן שָׁלַח הַקָּדוֹשׁ בָּרוּךְ הוּא מַגֵּפָה בְּצֹאנוֹ שֶׁל לָבָן וְנִשְׁתַּיְּרוּ מְעַט, מֵהָכָא, שֶׁנֶּאֱמַר וְיַעֲקֹב רוֹעֶה אֶת צֹאן לָבָן הַנּוֹתָרוֹת, שֶׁנּוֹתְרוּ מִן הַמַּגֵּפָה, כְּדֵי לְהַפְרוֹת וּלְהַרְבּוֹת צֹאנוֹ לְרַגְלוֹ שֶׁל יַעֲקֹב. מִכָּאן אַתָּה אוֹמֵר יֵשׁ רֶגֶל מַחְרֶבֶת בַּיִת, וְיֵשׁ רֶגֶל מְבָרֶכֶת בַּיִת, שֶׁנֶּאֱמַר (לעיל פסוק ל) "וַיְבָרֵךְ ה' אוֹתְךָ לְרַגְלִי".