Indra is worshiped in the fifth sukta of the first division of Rigveda. Its sage is Madhuchchhanda. The verse used in this is Gayatri. The total number of mantras in this is 10.
आ त्वेता नि षीदतेन्द्रमभि प्र गायत । सखायः स्तेमवाहसः ॥ 1 ॥
Indra is worshiped in the first verse of this Sukta. Rishi says – O friend who praises, praise! To please Indra, come and sit here and sing his praises.
पुरूतमं पुरूणामीशानं वार्याणाम् । इन्द्रं सोमे सचा सुते ॥ 2 ॥
Through this verse, the sages say – gather together and jointly research Somras and pray with the praises of the destroyer of enemies, Aishwaryawan Indra.
स घा नो योग आ भुवत् स राये स पुरंध्याम् । गमद्वाजेभिरा स नः ॥ 3 ॥
Through this mantra, the sage prays to Indra for material happiness and speaks – May that Indra get us through his various powers and fill us with wealth and grains and give us permission by intensifying our efforts.
यस्य संस्थे न वृण्वते हरी समत्सु शत्रवः । तस्मा इन्द्राय गायत ॥ 4 ॥
The sages say through this mantra – sing the wonderful qualities of that Indra, in front of whose chariot with horses in the summer land, the enemies cannot stand.
सूतपावने सुता इमे शुचयो यन्ति वीतये । सोमासो दध्याशिरः ॥ 5 ॥
Sages say – this refined and filtered, curd mixed Somras should be obtained automatically for the sake of Indra who drinks Som.
त्वं सुतस्य पीतये सद्यो वृद्धो अजायथाः । इन्द्र ज्यैष्ठयाय सुक्रतो ।। 6 ।।
The sage says – O great Karma Indra! You are always ready to rise among the gods through Sompan.
आ त्वा विशन्त्वाशवः सोमास इन्द्र गिर्वणः । शं ते सन्तु प्रचेतसे ॥ 7 ॥
Praising Indra through this verse, the sage says – Praiseworthy O Indra! May this Soma, which is present in all the three monsoons, always be in front of you and be happy for you and enrich your knowledge.
त्वां स्तोमा अवीवृधन् त्वामुक्था शतक्रतो । त्वां वर्धन्तु नो गिरः ॥ 8 ॥
Rishi says – O Shatkarma Indra! May you attain growth through praises. May these stotras recited by our voice increase your importance.
अक्षितोति: सनेदिमं वाजमिन्द्रः सहस्रिणम्। यस्मिन् विश्वानि पौंस्या ॥ 9 ॥
Through this verse, Rishi Devraj prays to Indra and says – May Indra, who is powerful, strong and gives strength and bravery, give us the ability to support thousands and let us consume food in the form of Somra, which exists in many forms.
मा नो मर्ता अभि द्रुहन् तनूनामिन्द्र गिर्वणः । ईशानो यवया वधम् ॥ 10 ॥
The sages say – Praise be to Indra, the one who gives us protection! No one should ever make us violent. No enemy can harm our body.