Verse 1.8.6

तं ह शिलकः शालावत्यश्चैकितायनं दाल्भ्यमुवाचाप्रतिष्ठितं वै किल ते दाल्भ्य साम यस्त्वेतर्हि ब्रूयान्मूर्धा ते विपतिष्यतीति मूर्धा ते विपतेदिति ॥ १.८.६ ॥

taṃ ha śilakaḥ śālāvatyaścaikitāyanaṃ dālbhyamuvācāpratiṣṭhitaṃ vai kila te dālbhya sāma yastvetarhi brūyānmūrdhā te vipatiṣyatīti mūrdhā te vipatediti || 1.8.6 ||

6. Śilaka Śālāvatya said to Caikitāyana Dālbhya: ‘O Dālbhya, your Sāma is then without a base. If someone knowledgeable about Sāma would now say [that your statement is wrong, and if he curses you saying,] “Your head will fall [if what you say turns out to be wrong],” your head will really fall’.

Word-for-word explanation:

Tam ha śilakaḥ śālāvatyaḥ caikitāyanam dālbhyam uvāca, Śilaka Śālāvatya said to Caikitāyana Dālbhya; vai kila te dālbhya sāma, your Sāma is, O Dālbhya; apratiṣṭhitam, without a base; yaḥ tu etarhi brūyāt, if anyone says now; te mūrdhā vipatiṣyati iti, your head will fall [if your statement about Sāma is found to be wrong]; te mūrdhā vipatet iti, your head will surely fall.

Commentary:

Śilaka said to Dālbhya that Sāma cannot have heaven as its support. He then quotes scriptures that what he says is true. He also adds that Dālbhya might be careful not to give the impression that he has any doubt about this. If he does, he will then risk being cursed by people who know the Sāma very well. They may curse him saying that his head will fall.

Whether Dālbhya’s head will fall or not is a different matter. If you commit a mistake, you surely have to pay for it. The measure of your punishment, however, is decided by many factors.