תּלמוד אויף ויקרא 24:3

Ma'aser Sheni - [we] don't weigh against it golden dinars [coins of another denomination], even [in order] to redeem with them other Ma'aser Sheni It's alright if you say that Rav and Shmu'el disputed about lighting from flame to flame, but with a matchstick [even] Shmu'el forbade - this [baraita] would not be a refutation, but if you say that [Shmu'el] also permitted [lighting from candle to candle] with a matchstick - this [baraita] would be a refutation [of Shmu'el]! Rabbah said: it is a [rabbinical prohibitive] decree - lest one not precisely balance one's measures, and spend them [the excess coins] for ordinary [i.e., non-sacred] things.

Rav Sheshet responded [bringing a baraita]: (Leviticus 24:3) "Outside the veil of testimony...shall he [Aaron] arrange..."; now, does He [G-d] need its light?! Was it not that all forty years that Yisrael walked in the desert, they walked only by His light? Rather, it is testimony to all inhabitants of the world that the Shechina dwells in Israel! What is that testimony? Rav said: it is the western light [of the menorah, in which he [the kohen] places a measure of oil equal to the others, yet from it he lights and with it he concludes! Here, since the candles are fixed [in the menorah, it is not possible unless he takes them and lights - this is a difficulty both for the one who says [that Rav's reasoning is] because of degrading the mitzvah and for the one who says [that Rav's reasoning is] because of reducing the mitzvah!